Boyle, Robert

(1627-1691), natural philosopher

by Michael Hunter

© Oxford University Press 2004 All rights reserved

Boyle, Robert (1627-1691), natural philosopher, was born on 25 January 1627 at Lismore Castle in the province of Munster, Ireland, the fourteenth child and seventh and youngest son of Richard Boyle, first earl of Cork (1566-1643), lord high treasurer of Ireland, and his second wife, Catherine (c.1588-1630), daughter of Sir Geoffrey Fenton, a literary scholar and principal secretary of state for Ireland. His father, known as the Great Earl, was one of the self-made men of the seventeenth century; having arrived in Ireland in 1588 with virtually no money, he lived to be one of the wealthiest subjects in the kingdom. Of Boyle's thirteen surviving brothers and sisters, many went on to subsequent eminence. They included Richard Boyle, first earl of Burlington and second earl of Cork, Katherine Jones, Viscountess Ranelagh, Roger Boyle, first earl of Orrery, and Mary Rich, countess of Warwick. Their prominence evidently owed at least something to the formative influence of their father's strong personality; he was alone responsible for his children's upbringing after the death of his wife in 1630. Some of Boyle's siblings (such as Mary, later countess of Warwick) seem to have had a somewhat tempestuous relationship with the Great Earl, but Boyle's recollection was that he was his father's special favourite; this did not, however, preclude the earl's insisting that Robin, as his parents called him, should, like his elder brothers, be sent away from home at an early age, by which time Boyle had evidently acquired the stutter which he was never fully to overcome.

Early life and education
In 1635, when he was eight, Boyle was sent to Eton College with his brother Francis, later Viscount Shannon. The boys were placed under the tutelage of the headmaster, John Harrison. From the outset Boyle distinguished himself by his studiousness: 'he prefers Learning afore all other vertues or pleasures' (Maddison, Life, 11n.), his father was informed, though Boyle subsequently recalled his lack of 'Inclination to Latin' (Hunter, Boyle by Himself, 26) which had to be rectified at a later date. He also commented in retrospect on the taste for history and for the gallant deeds of heroes of antiquity that he developed at this time; his enthusiasm, he claimed, was especially for the writings of Quintus Curtius and Sir Walter Ralegh. At Eton he was first introduced to romances, and specifically the story of Amadis de Gaule, while he discovered the virtues of algebra as a means to control his thoughts. In 1638 their father took Boyle and his brother away from Eton, and for a while they were tutored by William Douch, a clergyman to whom Cork had given the vicarage of Stalbridge in Dorset, where his chief English estate was situated.

In 1639, again in the company of his brother, Boyle embarked on a continental tour. Their guardian in their travels was Isaac Marcombes, a French protestant who had earlier conducted Boyle's elder brothers on a similar tour. After travelling through France, they settled at Geneva, Marcombes's home town, where they stayed for twenty-one months. Boyle's studies during this stay and during his subsequent stay at Geneva in 1642-4 covered a range of topics including ethics, history, natural philosophy of a fairly conservative variety, and fortification. In his autobiography Boyle recounted a conversion experience which he had at this time, occasioned by an awe-inspiring thunderstorm, which he claimed had a formative influence on his entire subsequent life.

In 1641 the two Boyle boys and Marcombes set out for Italy. Boyle's recollections of this visit are again recounted in his autobiography, including their visit to Florence, where he heard of the death of Galileo, whose works he was just then perusing, and to Rome, where he visited the sights and observed the pope with the disdain appropriate to a well-born young protestant. Subsequently the party returned to France, where problems arose due to the outbreak of the Irish rising and the sudden termination of the funds that they had been receiving from their father. As a result, while Francis returned to Ireland to fight, Boyle spent two more years studying in Geneva.

Boyle returned to England in 1644 and initially spent some months in London: virtually the only surviving record of this episode is his vivid later recollection of his homecoming and reunion with his sister Lady Ranelagh, with whom he had already developed an especially close relationship and in whose house he stayed for four and a half months. In 1645 Boyle moved to Stalbridge, Dorset, where his father had bequeathed him the manor house and estate. There Boyle spent much of the next decade, though it is possible that he travelled to France in 1645, while from February to April 1648 he visited the Netherlands. He also travelled regularly to London, and it was probably during these visits that he took part in the activities of a body called the 'Invisible College', which has been the subject of intense speculation on the basis of brief references in three of Boyle's letters of 1646-7, though none of these gives more than vague clues as to its personnel and aims. In addition, from 1647 onwards, correspondence survives between Boyle and the intelligencer Samuel Hartlib, who frequently reported on Boyle's views and activities in his Ephemerides from 1648 until the end of the 1650s.

At Stalbridge in the mid-1640s Boyle embarked quite self-consciously on a career as a writer. Contrary to what might be expected from his later publications, his efforts were not initially devoted to science. His first project (in 1645-6) was his Aretology, a somewhat stilted treatise on 'Ethicall Elements' intended to lay down the rudiments of morality as a basis for the pursuit of virtue. Subsequently Boyle experimented with other literary genres, and the best of his compositions of this period display a real vigour and solicitude for stylistic elegance. Among them were pious essays, and reflections on scriptural passages and events which formed the basis of his later Occasional Reflections (1665). Others were influenced by his reading of French romances, including imaginary lives, speeches, and a romance, The Martyrdom of Theodora and of Didymus, said by Dr Johnson to be the first work 'to employ the ornaments of romance in the decoration of religion' (J. Boswell, Life, 1.312): the romance was partially published in much altered form in 1687, though the original version also survives. Other compositions included letters presenting moralistic prescriptions to fictional addressees, a number of which survive, some of them forming part of an ambitious work of which one part was ultimately to appear in modified form as Some Motives and Incentives to the Love of God (1659), usually referred to by its running title, Seraphic Love.

Two other significant writings of this phase in Boyle's career are his autobiographical 'Account of Philaretus during his minority' of 1648 or 1649, which recalls memories of his childhood and continental travels, and his 'Invitation to a free and generous communication of secrets and receits in physick', addressed to Hartlib and almost certainly written in 1649, which was to become Boyle's first published work in 1655. This was a formative period in Boyle's life, even though his writing subsequently shifted to quite different topics. The concern for morality seen in his writings of this period was the source of the concern for probity and self-control that he internalized and sought to exemplify in later life. In addition, remnants of his literary aspirations survived.

The turn to science
In 1649-50 a major change in Boyle's preoccupations occurred. Most importantly, in 1649 he successfully set up a laboratory at his house in Stalbridge; the experiments that this enabled him to carry out seem immediately to have fascinated him to an extent that transformed his career, and from that summer onwards his work shows an enthusiasm for experimental knowledge that had earlier been missing, though a legacy of his earlier aspirations may be discerned in his ambition to put such experimental knowledge to apologetic use. Writings that survive from this period display an acute concern about the threat of irreligion posed by the predominant Aristotelian natural philosophy of the day, combined with a conviction that the best means to offset this was a recourse to experimental data. His empirical investigations at this point concerned a range of chemical and alchemical trials involving mercury and other substances, while he also refers to his use of a microscope to observe the minute structure of living things, and reveals a preoccupation with collecting data about 'effluvia' and other natural phenomena that foreshadows later interests. Intellectually his mentors at this stage in his career were such sixteenth-century and early seventeenth-century authors as Paracelsus, Bernardino Telesio, Francis Bacon, Tommaso Campanella, and J. B. van Helmont. Boyle also expressed his sense of solidarity with 'the Chymists', and it was evidently in a chemical context that he first encountered atomist ideas to which he gave expression in his treatise 'Of the atomicall philosophy' (c.1652-4). Moreover, he forged links with other figures who shared his interests, notably Hartlib's son-in-law, Frederic Clodius, and the American alchemist George Starkey, with whose instructions Boyle prepared alchemical products, including a philosophical mercury and the Helmontian drug ens veneris.

A further key development of the years around 1650 was that Boyle became interested in the biblical languages--Greek, Hebrew, Chaldaic, Syriac, and Arabic--and in the scholarship that had been devoted to the elucidation of biblical and classical history since the Renaissance. The stimulus to the former, Boyle attributed to the scholar and divine James Ussher, archbishop of Armagh. Its fruit is to be seen particularly in the 'Essay of the holy scriptures' (c.1652-4), part of which has survived in manuscript, while part of it he adapted to form his Some Considerations Touching the Style of the Holy Scriptures, published in 1661. Such interests were shared by Boyle's friend and west country neighbour John Mallet, and were discussed in letters between the two men. To this episode can be traced the expertise in biblical languages which Boyle retained for the rest of his life and by which contemporaries were impressed.

Between June 1652 and July 1654 Boyle spent all but about three months in Ireland. The reasons for this visit are not entirely clear, but they probably related to the Boyle family's landed interests there. In Ireland Boyle had contact with William Petty, then in Dublin, who apparently introduced him to anatomical dissection, a topic on which he reported with enthusiasm in letters to Hartlib. At this time he also wrote 'a short essay concerning chemistry, by way of a judicium de chemia & chemicis', which apparently contained the germ of his critique of 'vulgar chymists' in his Sceptical Chymist (1661). Towards the end of his Irish stay Boyle fell seriously ill with an anasarca or dropsy: complications developed, which he vividly recounted in his later years, and these affected not least his eyesight, which he claimed never fully recovered. The result of this was that for the rest of his life Boyle was dependent on amanuenses to write his ideas down for him, and this gave his style a digressiveness reflecting his actual manner of speaking, which contrasts with the pursuit of elegance according to literary models which characterized his writings of the mid- to late 1640s.

Interregnum Oxford
Late in 1655 or early in 1656 Boyle moved to Oxford, joining the lively group of natural philosophers centred on Wadham College under the auspices of John Wilkins, who had been intruded as warden there by the parliamentary commissioners; the group also included such figures as the Anglican physician Thomas Willis. After Wilkins moved to Trinity College, Cambridge, in 1659, its meetings took place at Boyle's lodgings in the High Street. The significance of this group for the later development of English science has often been emphasized, and it clearly had a major impact on Boyle. It was now that he seriously confronted the writings of the major continental natural philosophers, notably Gassendi and Descartes, refining and modernizing the ideas that he had acquired from the essentially Renaissance authors whom he had encountered earlier in the decade. In the case of Descartes, though Boyle had been aware of his writings earlier, he claimed that the figure who 'made him understand Des Cartes' Philosophy' was Robert Hooke, who entered Boyle's employ at this time and helped him in some of his crucial experiments (J. Aubrey, Brief Lives, ed. A. Clark, 1898, 1.411).

In addition, it seems that at this time Boyle discovered more of the intrinsic interest of knowledge about the natural world, as against the apologetic motives that had dominated his initial espousal of experimental learning earlier in the 1650s. He now also became aware of a further threat which a reformed natural philosophy might have to withstand, namely that posed by the ideas of Thomas Hobbes, whose version of the mechanical philosophy had been attacked as pernicious and implicitly atheistic by one of the leading figures in the Oxford group, Seth Ward, earlier in the 1650s. The threat of materialistic atheism which Hobbes seemed to exemplify added a new dimension to Boyle's apologetic concerns, which was to remain with him for the rest of his life.

The late 1650s, following Boyle's move to Oxford, saw an extraordinarily intense programme of research and writing on his part. The numerous books on different aspects of natural philosophy which he now began or completed set the pattern for his entire subsequent intellectual career, and it was on them that his later impact was substantially based. At this time he wrote the bulk of Some Considerations Touching the Usefulness of Experimental Natural Philosophy (1663, 1671): the first part, which celebrates the religious value of study of the natural world, had been begun earlier but was revised and extended at this time, while the first section of the second part, dealing with the value of science to medicine, was apparently now newly written. This immense compilation--which, in the course of expounding its theme, divulged a vast number of cures which Boyle had come across and tried--was to prove his most extensive medical work and it was widely cited in the debates on medical practice of the time. Boyle also wrote extensively on the application of science more generally, and some sections of these writings were to be published as the second section of part 2 of Usefulness in 1671, though others were abandoned. A key aim of this section was to show that practical inventions and advancements in technique are grounded in theoretical natural philosophy, and to defend the new experimental sciences against critics who doubted their social utility.

More important still was Boyle's Certain Physiological Essays (1661). This collection comprised a series of essays presenting a very subtle view of experiments and their rationale, and illustrating the way in which they could be deployed to provide an empirical foundation for Boyle's version of the mechanical philosophy, in which natural changes and sensory effects could be attributed to interactions between minute bodies that he called corpuscles. He adopted the name corpuscularianism to avoid the irreligious overtones that atomism had inherited from classical antiquity. In addition to the essays on experimentation generally, which included two key discourses on the significance of unsuccessful experiments, Boyle also laid out some of his specific experimental findings in this collection, perhaps most crucially in 'A physico-chymicall essay, containing an experiment with some considerations touching the differing parts and redintegration of salt-peter'--often referred to by Boyle as his 'Essay on nitre'. There he experimentally demonstrated how the changes that could be brought about in saltpetre by chemical means could be explained entirely in terms of the size and motion of corpuscles, without the need for any of the explanations in terms of 'forms' and 'qualities' associated with traditional scholastic science.

Boyle was later to pursue these ideas in various other works, the most notable of which was his The Origin of Forms and Qualities (1666), in which he attacked the predominant scholasticism of the period, trying to wean his contemporaries away from the essentially qualitative modes of thinking associated with Aristotelian ideas, and to indicate the superior intelligibility of mechanical explanations of phenomena. This was accompanied by more extensive collections of experimental and observational data intended to vindicate corpuscularian explanations of the natural world, begun while he was at Oxford, the most notable of which were Experiments and Considerations Touching Colours (1664) and New Experiments and Observations Touching Cold (1665). These writings were an important source for Locke's well-known distinction between 'primary' and 'secondary' qualities.

In the late 1650s Boyle wrote his most famous work, The Sceptical Chymist (1661), a somewhat discursive dialogue which attacked both the peripatetic doctrine of four elements and the Paracelsian view of the tria prima, while at the same time attempting to persuade the 'chymists', from whom he had initially learned so much as an experimenter, that they needed to adopt a more philosophical approach in their study of nature. Like Certain Physiological Essays, the work also sought to vindicate corpuscular explanations of chemical reactions, in the course of doing so retailing much information about experimental investigations which Boyle had carried out.

Alongside this, Boyle's New Experiments Physico-Mechanical, Touching the Spring of the Air and its Effects (1660), written in a relatively short period in 1659 and published almost as soon as it was finished, recounted experiments using a vacuum chamber or 'air pump' which he constructed with the assistance of Hooke. Rejecting the scholastic notion that nature could not tolerate a vacuum, he showed how it was perfectly possible to produce one, and this enabled him to illustrate the characteristics and functions of the air by studying the effects of its withdrawal on flame, light, and living creatures. He also argued that certain characteristics of the air could only be explained in terms of the ingenious hypothesis that it had a certain weight and 'spring'. Subsequent to the publication of the New Experiments, and partly as a result of the well-publicized controversies which followed it, the 'air pump' became part of the standard equipment of laboratories, and was widely diffused throughout scientific Europe.

Apart from his scientific work, Boyle's Oxford period was also notable for the religious contacts that he made. The most important of these was with the Calvinist theologian Thomas Barlow, then Bodley's librarian, who was to become bishop of Lincoln in 1675. Barlow was well known for his skill in cases of conscience, or casuistry, and--both at this time and later--he provided Boyle with much advice on such matters; in 1659 he also acted as an intermediary between Boyle and the former regius professor of divinity, Robert Sanderson, whom Boyle had offered to remunerate if he prepared for publication his celebrated casuistical lectures, given at Oxford in the 1640s before he was ejected by the parliamentary visitors. At this point in Boyle's life his active engagement with missionary projects first became apparent: in 1660 he paid the cost of printing a translation into Arabic by the scholar Edward Pococke of Grotius' De veritate religionis Christianae, and over the next few years he contributed to the cost of the publication of a Turkish catechism and New Testament and helped the Lithuanian exile Samuel Chylinski, who had translated the Bible into his native language and was seeking to get it published. From this time also dates Boyle's concern with evangelizing the North American Indians.

The Restoration and its aftermath
The aftermath of the Restoration in 1660 saw a peak of public activity on Boyle's part, something which he had shunned hitherto. In 1660 he encouraged his friends Sir Peter Pett and Thomas Barlow to write tracts on the pressing political question of what degree of toleration was desirable and practicable. He was also a member of the council for foreign plantations from 1661 to 1664, and in 1662 became governor of the Company for the Propagation of the Gospel in New England. A note made by Bishop Gilbert Burnet on an interview with Boyle later in his life records that both the earl of Clarendon and the earl of Southampton tried to encourage Boyle to become a bishop, an invitation that he declined on the grounds that 'he never felt the Inward Vocation so he should be in an Imployment against the grain with him' (Hunter, Boyle by Himself, 33).

Of the activities that Boyle embarked on in the aftermath of the Restoration, only one proved sustained, his governorship of the New England Company; otherwise, the chief long-term legacy of this burst of involvement with the public sphere on Boyle's part was a grant to him from Charles II of impropriations of former monastic lands in Ireland. This may initially have been intended to support the profuse experimental activity which Boyle had already been carrying on in the 1650s and which was to continue for the rest of his life but--evidently at least partly due to recriminations that followed the grant on the part of disappointed applicants, notably representatives of the Irish church--Boyle resolved to spend the proceeds on 'pious uses', in supporting both the Irish clergy and the evangelical activity in New England to which he was by this time committed.

The most significant change in Boyle's career about 1660 was that he began to publish. Prior to 1659, Boyle's only publication was a tract addressed to Hartlib (composed in 1649) that appeared in Chymical, Medicinal, and Chirurgical Addresses Made to Samuel Hartlib Esquire (1655). In 1659 Boyle orchestrated the publication of an English translation of a brief work by the Dutch anatomist Lodewijk de Bils, The Coppy of a Certain Large Act ... Touching the Skill of a Better Way of Anatomy of Mans Body, and his care over its promotion foreshadows his later concern about his own writings. The same year also saw the publication of Seraphic Love, while from 1660 onwards a veritable torrent of works followed, beginning with New Experiments ... Touching the Spring of the Air and including many of the works composed in the 1650s. Boyle's writings were published not only in English; he also made careful arrangements to have them translated into Latin by Oxford dons and others, and their subsequent publication by booksellers in Oxford and London ensured that they were widely read in the international scholarly community. Indeed, it is not surprising that one of his publishers later claimed that he had become known throughout Europe as 'the English philosopher'.

It was a tribute to the new-found celebrity that Boyle enjoyed in the early 1660s that he was the subject at this time of published attacks, particularly on his first scientific book, New Experiments ... Touching the Spring of the Air. Works criticizing this were brought out by Thomas Hobbes, by the English Jesuit Francis Linus, and by the Dutch scholar Anthony Deusing, and Boyle replied at length to Hobbes and Linus, disposing of Deusing in briefer comments in the preface to the Latin edition of his defence against Linus. In the course of elaborating his views, in A Defence of the Doctrine, Touching the Spring and Weight of the Air, Boyle divulged what later became known as Boyle's law, namely that the quantitative relationship between the volume and pressure of a gas was an inverse one; in Boyle's language that 'pressures and expansions [are] in reciprocal proportion' (Works, 3.59).

The controversy with Hobbes has proved of much interest to historians, partly because it involved an attack on the newly established Royal Society combined with an attack on Boyle's methods of investigation. Boyle explicitly recognized this feature of Hobbes's approach: 'though some things in the Title Page [and] in the Book it self seem to make the chief Design of it to be the Disparagement of the Society', he wrote, 'yet the Arguments are for the most part levelled at some Writings of mine', and he expressed his surprise that an experienced writer would publicly attack an institution supported by his own patron, the duke of Devonshire. For his part, in An Examen of Mr T. Hobbes's 'Dialogus' (1662), Boyle used the opportunity to strengthen the grounds for experimental knowledge by contrasting it with Hobbes's method of arguing from plausible hypotheses, declaring that 'on the occasion of Mr Hobbs's Building a great part of his philosophy upon no surer a ground ... we may hence learn how little Reason there is to blame me, as he is pleas'd to do, for making Elaborate Experiments' (Works, 3.115, 120).

Such controversy did not affect the rise of Boyle's star, which had been enhanced by the foundation in 1660 of the Royal Society, devoted to experimental philosophy of the kind pursued by the group at Oxford to which Boyle had belonged in the 1650s. He was present at the society's inaugural meeting on 28 November 1660, and was active at its meetings throughout its early years. He also benefited from the promotional activities on behalf of the society and the new science undertaken at this time by its first secretary, Henry Oldenburg, who had been a close contact of Boyle since he had tutored Boyle's nephew Richard Jones, later first earl of Ranelagh, in the 1650s. The most significant of Oldenburg's initiatives was his inauguration in 1665 under the society's auspices of the Philosophical Transactions: in addition to carrying frequent contributions by Boyle--some of them almost of book length--the new journal included fulsome reviews of each of his books as they came out. Boyle was also praised as emblematic of the Royal Society's scientific work in Joseph Glanvill's apologia, Plus ultra (1668). The significance of the society for Boyle's intellectual activities in the 1660s is underlined by the fact that it was in response to its request for a report on the work of the French natural philosopher Blaise Pascal, in 1664, that he wrote his Hydrostatical Paradoxes (1666).

During the 1660s Boyle continued to live in Oxford, and on 8 September 1665 he was created doctor of physic there, the only academic degree he ever acquired. However, the journal books of the Royal Society reveal that he was frequently in London from 1661 onwards, and in 1665-6 he was clearly in the capital throughout the episode involving the perplexing Irish 'stroker' (so called because he seemed to heal people by stroking their bodies), Valentine Greatrakes, in the debate over whom Boyle became involved when an iconoclastic tract on the subject was dedicated to him by the controversialist and physician Henry Stubbe. Boyle objected to Stubbe's explanation of the phenomenon both on scientific and on theological grounds, and subsequently he took a close interest in Greatrakes's cures, attending more than sixty healing sessions, and in one instance participating in the stroking himself.

In 1668 Boyle left Oxford and moved to London, where for the rest of his life he shared a house in Pall Mall with his sister Lady Ranelagh, the closeness of his relations with whom was commented on by contemporaries; even this sojourn, however, was punctuated by occasional stays in lodgings elsewhere in London and in the country. Boyle seems to have settled in well at the Pall Mall house, with his own quarters and even his own laboratory, which was evidently located in a 'back-house'. The laboratory became a well-known place of encounter with him, and was much frequented by foreign and other visitors. Indeed, such an attraction for visitors from overseas did the great philosopher become that John Evelyn claimed that 'one who had not seene Mr Boyle, was look'd-on as missing one of the most valuable Objects of our Nation' (Hunter, Boyle by Himself, xlii).

Later years and death
In 1670 Boyle suffered a severe stroke which, in the words of his sister Mary, brought him to 'deathes doore'. Thereafter, his activity at the Royal Society dwindled and he kept more to himself, but he was as active as ever in his publishing activity. His profuse experimental work of the 1650s and 1660s continued throughout the following decade, being represented perhaps most notably by his Experiments, Notes, &c., about the Mechanical Origin or Production of Divers Particular Qualities (1675), aimed (like his earlier books) to vindicate corpuscular explanations against scholastic ones. He also brought out sequels to his New Experiments ... Touching the Spring of the Air in which experiments using a vacuum pump were expounded, the last, first published in Latin in 1680, largely written by his then assistant, Denis Papin. In addition Boyle investigated the intriguing properties of phosphorescence in Aerial Noctiluca and Icy Noctiluca (1680-2).

In the 1670s Boyle also published a variety of shorter, more controversial treatises. Despite his professed reluctance to become involved in controversy, he attacked Henry More in An Hydrostatical Discourse (1672) for More's misuse of Boyle's experimental findings and he returned to the attack on Hobbes; he also published an attack on the chemists who he felt were exaggerating the explanatory power of the interaction between acid and alkali. In addition, he published more speculative treatises such as Of the Systematical or Cosmical Qualities of Things (1670), while the late 1670s apparently saw a peak in Boyle's interest in alchemy. In 1676 he published an article in the Philosophical Transactions on the incalescence of mercury with gold, which stimulated a revealing response from Newton (who did not think that such matters ought to be revealed in public). In 1678 Boyle brought out a short tract, Of a Degradation of Gold Made by an Anti-Elixir. These publications reflected an exceptional intensity at this time in Boyle's contact with people who claimed to have witnessed alchemical processes, together with a burst of epistolary communication with a shadowy circle of French alchemists in which Boyle's chief contact was one Georges Pierre.

The decade was also notable for the publication of theological writings by Boyle, some of them works which he had compiled in the 1660s but had put to one side at that time, such as Excellency of Theology, Compar'd with Natural Philosophy (1674), to which was appended an important shorter work by Boyle, 'Considerations about the excellency and grounds of the mechanical hypothesis', often regarded as the classic exposition of his philosophy.

In the last decade of Boyle's life his experimental programme was expressed in such works as Experiments and Considerations about the Porosity of Bodies (1684) and his treatise on mineral waters. He also brought out his Experimenta et observationes physicae (1691), the last work published in his lifetime, which invokes an explicitly Baconian inspiration for its combination of experimental and reported data. However, perhaps the most important works that Boyle published in this decade represented his mature reflections on major theological and philosophical issues, notably A Discourse of Things above Reason (1681), A Free Enquiry into the Vulgarly Receiv'd Notion of Nature (1686), A Disquisition about the Final Causes of Natural Things (1688), and The Christian Virtuoso (1690). In these he made a profound contribution to contemporary debates regarding the true relationship between God and the natural world, and man's potential for comprehending this.

Various works by Boyle on medical topics also appeared. These were the first such publications since the medical section of his Usefulness published in 1663. In the aftermath of that work, Boyle had considered developing the rather guarded criticisms of orthodox medical practice that it contained into an outright assault on the contemporary 'methodus medendi'. Though he wrote at least part of this work, however, he decided against publishing it. Instead, his later publications in this field dealt mainly with what might be described as 'medical science', comprising his Memoirs for the Natural History of Human Blood (1684), Of the Reconcileableness of Specifick Medicines to the Corpuscular Philosophy (1685), and Medicina hydrostatica (1690). He also brought out a collection of medical recipes in 1688; initially this was privately printed but a properly published edition appeared posthumously in 1692, with sequels appearing thereafter. The 1680s also saw Boyle take a leading part in a project for making salt-water sweet, for which his nephew Captain Robert Fitzgerald obtained a patent in 1683 but which met with only partial success.

Boyle's active religiosity is much in evidence in the later years of his life. His philanthropy was well known and he backed various projects such as that for the publication and distribution of the Bible in Gaelic, both in Ireland and in the Scottish highlands; he also supported the churchman Burnet while he was producing his seminal History of the Reformation of the Church of England in 1680. In that year Boyle refused to become president of the Royal Society, attributing his decision to his reluctance to take the oaths required under the Test Acts--reflecting a 'scrupulosity' much in evidence in his later years. Various epistolary discourses on casuistical questions addressed to him by Barlow survive from the early 1680s, while a more extraordinary survival comprises Boyle's own notes on his confessional interviews with Bishop Gilbert Burnet and Bishop Edward Stillingfleet in 1691, which reveal his extreme scruples on matters of conscience affecting his financial affairs, and the blasphemous thoughts that assailed him. Such scruples also influenced his approach to the natural world, since a further interview with Burnet--who evidently replaced Barlow as Boyle's chief confidant in the last years of his life--makes clear Boyle's ambivalence about alchemy on the grounds that the insights which it offered might be illicitly achieved by malevolent spirits.

By the later 1680s Boyle's health was declining. In 1688 he issued a strange broadsheet advertisement apologizing for the imperfection of his publications and blaming it on his anxiety to put as much as possible into print before it was too late. He also curtailed his preparedness to receive visitors. In 1689 he resigned his governorship of the Company for the Propagation of the Gospel in New England on health grounds. It was apparently due to further worries about his health in the summer of 1691 that he drew up an elaborate will on 18 July, though he continued to add codicils dealing with various aspects of his affairs thereafter; his solicitousness about such matters was enhanced by concern over his finances due to the unsettled state of Ireland at the time. A climax of activity in cataloguing his papers in that year evidently reflected a similar sense that his death was not far off.

Boyle's beloved sister Lady Ranelagh died on 23 December 1691 and he himself died a week later, in the early hours of 31 December 1691; he was buried in the chancel of St Martin-in-the-Fields on 7 January 1692, when the funeral sermon was preached to 'a vast crow'd' by Gilbert Burnet (Maddison, Life, 185). That year and the next saw the publication of posthumous works under the aegis of John Locke. One of the numerous codicils to Boyle's will provided for the setting up of a series of lectures for the defence of the Christian religion against atheists and others, the so-called Boyle lectures. The first series of these was delivered by the scholar and divine Richard Bentley in 1692. Other charitable bequests under Boyle's will followed later in the 1690s and into the early eighteenth century.

Boyle's thought and influence
The central fact of Boyle's life from his adolescence onwards was his deep piety, and it is impossible to understand him without doing justice to this. His friends remarked after his death how 'the very Name of God was never mentioned by him without a Pause and a visible stop in his Discourse' (Hunter, Boyle by Himself, 48), and this slightly disconcerting habit was symptomatic of the overriding significance for him of his deep theism. Burnet's funeral sermon rightly stressed how Boyle's life was devoted to the service of God and to the defence and propagation of the Christian religion, which he carried out by various means. One was by deploying for charitable purposes the wealth that he acquired both by his high birth and by the grant of impropriations to him by Charles II at the Restoration. His support for missionary enterprises was supplemented by philanthropy on a smaller scale: throughout his life he devoted funds to the support of the needy, be they rural ministers in Ireland, impecunious scholars, or religious refugees from overseas, notably Huguenots. He was similarly solicitous in placing the medical expertise that he acquired in the course of his career at the disposal of the necessitous, aspiring in this to a truly Christ-like role.

Boyle's chief lifework, however, was the pursuit of his religious goals by means of intellectual activity. In the 1640s his preoccupation was the encouragement of piety and of high standards of morality among his peers. Thereafter, his concern was above all with promoting his theistic ends by utilizing the findings from the profuse study of nature in which he engaged from about 1650 onwards. Boyle was fiercely hostile to views of nature that he saw as detracting from a proper appreciation of God's power in his creation. Among these, his principal target was the Aristotelian world view which was prevalent in his day, though he was equally hostile to other intellectual traditions which he saw as pernicious, notably the materialism associated with Hobbes, which contemporaries frequently saw as indistinguishable from atheism.

The activities in which Boyle engaged in order to confront these threats were twofold, and both were pursued with an energy amounting to obsessiveness which characterized him in all areas of his life. That which emerged earliest was writing. Apart from his published books, which number more than forty and comprise some 3 million words, further evidence of his activity as a writer survives in the Boyle archive, including drafts, notes, and sections of works that were not published in his time, some of which have been printed since, notably in volumes 13 and 14 of the new edition of his Works. Though he sometimes expressed diffidence about the manner in which he expressed himself, Boyle was generally content with the message that he put across in his numerous publications. Indeed, he was highly self-conscious about his Ďuvre, with strong views about authorship and the threat to it posed by plagiarism. In the 1660s he was behind various proposals put to the Royal Society to register authorship, and his defensiveness about his own writings grew as his life went on, particularly due to the extent to which he believed that he was the victim of intellectual piracy by writers and publishers in the 1670s.

Equally important was the second leading activity of Boyle's intellectual career, the experimentation which developed from about 1650. From the summer of 1649 Boyle spent much of his time in his laboratory, ceaselessly investigating chemical and other phenomena. The results of this appear not only in Boyle's published works but also among his papers, which include profuse accounts of repeated trials made over many years. Indeed, Boyle was an experimenter par excellence, both in theory and practice, eclectically building on precedents provided in the writings of Francis Bacon and in the procedures of the practical 'chymists' and other craftsmen which he consciously sought to graft into natural philosophy. In part he did so through the consideration that he gave to the method and rationale of experiments in Certain Physiological Essays and other works. Equally important was his experimental practice, which displayed an extraordinary ingenuity in devising trials which would reveal significant information about the phenomena he studied, combined with an unprecedented precision in observing their outcome. Indeed, Boyle's experimentation, like his writing--and, for that matter, his soul-searching in his spiritual life--was inspired by the obsessiveness that characterized everything he did, ensuring that he was never satisfied until sure that he had penetrated the innermost core of a subject.

Having executed his experiments, Boyle's persona as writer came to the fore, and he went to great pains to provide a detailed account of them so that others could follow as closely as possible the procedures that he had used in reaching the results that he reported. His hope was that his readers would accept the 'matters of fact' that he had established, whatever rival interpretations might be based on them. Indeed, his experimental accounts from the late 1650s onwards used increasingly sophisticated strategies to deal with the fact that it was impossible to reproduce all the exact circumstances of an experiment accurately in writing, providing a model for others which was widely followed. However, he did not limit himself to observations that he had made himself. He also included accounts of phenomena that he had been told of by others or had read about in books, a practice for which he explicitly cited the example of Bacon. Such books as his histories of cold and colours, or his later Experimenta et observationes physicae, are made up of a patchwork of such material, which Boyle saw as offering the basis on which a science of nature would ultimately be constructed.

When it came to the conclusions that might be derived from such data, Boyle was a little more ambivalent. He was hostile to the premature systematization that he saw as having blighted much science prior to his time, and the result was that he showed a reluctance to draw conclusions for which he was criticized by some more rationalistic thinkers of his day, such as Christian Huygens and Gottfried Wilhelm Leibniz. Nevertheless his empirical activity was underwritten by clear explanatory goals. In particular, from the 1650s to the end of his life he never swerved from his conviction that the universe was best understood according to mechanical principles, and he ceaselessly urged the superiority of these to the Aristotelian and other alternatives that flourished in his day. Such principles appealed to him not least because he saw them as supremely compatible with God's active role in the world.

Though Boyle took it for granted that explanations should be formulated in primarily mechanical terms he acknowledged that there might be intellectual differences within this basic framework, and his own views were quite flexible. Thus his interpretation of chemical phenomena took it for granted that corpuscles were endowed with chemical, as against strictly mechanical, principles, while various of the explanations that he adduced invoked 'intermediate causes', such as the concepts of weight and elasticity in the air. His corpuscularianism was itself eclectic, drawing on a range of sources and including concepts such as 'dregs' or 'denseness' which might be seen as at odds with a strict interpretation of the mechanical philosophy. Boyle had no illusions about the complexity of the world--it was partly for this reason that he was so insatiable in collecting information about it--and this was reflected by the interpretations of it that he formulated.

Indeed, Boyle ranged perhaps surprisingly far in the phenomena that he took seriously, with a truly Baconian sense that primacy should be given to establishing whether phenomena actually existed rather than dismissing them according to a priori criteria. Thus he toyed with the notion that there were 'cosmical qualities' transcending purely mechanistic laws in the universe, and he was also fascinated by authenticated reports of supernatural phenomena, on the grounds that these vindicated the reality of God's power in the world. His interest in alchemy fits into this context, since he was perfectly prepared to believe that unexpected phenomena of the kind that it revealed were real. Matters were complicated by his ethical qualms as to whether such knowledge might be illicit and hence to be avoided on moral grounds, but against this was the consideration that alchemy appeared to offer an empirical bridge between the natural and the supernatural realms which might provide irrefutable evidence of God's existence.

Boyle's major preoccupation was the relationship between God's power, the created realm, and man's perception of it, a topic on which he wrote extensively, in books mainly published in the 1680s though the views that they expressed may be traced in embryonic form in his earlier writings. In them Boyle laid stress on the extent to which God's omniscience transcended the limited bounds of human reason, taking up a position that contrasted with the rather complacent rationalism of contemporary divines such as Joseph Glanvill. He also reflected at length on the proper understanding of final causes, and in conjunction with this provided one of the most sophisticated expositions of the design argument in his period. Indeed, Boyle's significance for the history of science depends almost as much on the profound views on difficult issues put forward in these philosophical writings as it does on his experimental treatises.

In terms of his affiliations in the religious scene of his day, Boyle was somewhat independent. He conformed to the Church of England in 1660, and specifically stated his allegiance to the idea of a visible church, but he was unusually tolerant towards Catholics by the standards of most English protestants of his day, and he was singularly uninterested in many of the doctrinal debates by which the contemporary English church was riven. He also showed a marked sympathy for the views of those who, unlike him, felt unable to conform to the Anglican church at the Restoration, and his contacts extended even to those described at the time as 'enthusiasts'. The ecclesiastical group with whom he seems to have had the least sympathy were the high-churchmen who were in the ascendant during the Restoration decades, and there is some truth in a loose characterization of Boyle as a 'latitudinarian', so long as this is understood in a fairly flexible manner, as reflecting a general inclination to religious tolerance and a stress on the fundamentals of Christianity, rather than an insistence on comprehension along lines laid down by a triumphalist Anglican church. Equally important was his view that differences among Christians should be minimized in favour of an attack on atheists whose ideas all could agree in deprecating, which was to be institutionalized in the Boyle lectures.

As for Boyle's political views, in his mature years he was closely associated with the establishment and had personal contact with each of the Restoration monarchs. Prior to 1660 his primary commitment seems to been to political stability; although his views at that time (as later) remain substantially inscrutable, contemporaries noted that he always referred to the government of the day 'with an exactness of respect' (Hunter, Boyle by Himself, 25). He was also committed to national prosperity, taking an active interest in economic improvement and in maximizing the effectiveness of the navy. On the other hand, it is revealing that the brief period of active involvement in such affairs on his part which occurred in the early 1660s ended in disillusionment, and there is some evidence of his dissatisfaction with the laissez faire attitudes of the Restoration government. Boyle's sympathies seem to have been more with the egalitarian and interventionist ideals represented by Samuel Hartlib and his associates in the interregnum, with whom he had had close contacts. There is evidence that, in the later decades of the century, Boyle's strong feelings about the plight of the poor placed him somewhat at odds with the prevailing orthodoxy, especially on medical matters, where his views continued to echo the aspirations of the interregnum reform movement.

These were views, however, which Boyle publicly expressed only in muted form. Although scrutiny of his unpublished papers reveals strong feelings on such topical issues, these views only marginally affected his public persona. Neither were most contemporaries aware of the more stressful aspects of his religiosity, including the doubts that he suffered and the tortured conscience with which he had to live. During his career Boyle learned how to capitalize on those of his characteristics which went down well with his contemporaries, and to keep the more ambivalent aspects of his ideas to himself. Publicly, the image of Boyle in the eyes of most of his contemporaries, which is also the image which has come down to posterity, was one of serenity, of a lofty transcendence of the mundanities of the world in the pursuit of higher goals of truth and piety. This view was formulated with brilliant clarity in Burnet's funeral sermon, which heavily influenced the first full life of Boyle by Thomas Birch, published in 1744. Birch's Life has been the basis of almost all subsequent accounts of Boyle, while Birch and his collaborator, Henry Miles, also influenced his retrospective image by the extent to which they tidied up his archive, more or less consciously clearing away material which they saw as irrelevant to the image of the great and good man which they purveyed. The view of him that resulted was not untrue but merely incomplete. When their omissions are corrected, and Boyle is placed back into his proper historical context, he remains a remarkable figure. Today the achievement of this icon of the new science seems no smaller than it did to his early admirers.


The works of Robert Boyle, ed. M. Hunter and E. B. Davis, 7 vols. (1999-2000)
T. Birch, 'The life of the Hon. Robert Boyle', in The works of the Hon. Robert Boyle, ed. T. Birch, 2nd edn (1772),
M. Hunter, ed., Robert Boyle by himself and his friends (1994) [incl. Boyle's 'Account of Philaretus during his minority']
R. E. W. Maddison, The life of the Honourable Robert Boyle, F. R. S. (1969)
R. E. W. Maddison, 'The portraiture of the honourable Robert Boyle', Annals of Science, 15 (1959), 141-214
The correspondence of Robert Boyle, ed. M. Hunter, A. Clericuzio, and L. M. Principe (2001)
M. Hunter, Letters and papers of Robert Boyle: a guide to the manuscripts and microfilm (1992)
J. F. Fulton, A bibliography of the Hon. Robert Boyle, 2nd edn (1961)
M. Hunter, Robert Boyle reconsidered (1994) [incl. bibliography of writings on Boyle, 1941-93]
M. Hunter, 'How Boyle became a scientist', History of Science, 33 (1995), 59-103
M. Hunter, 'Casuistry in action: Robert Boyle's confessional interviews with Gilbert Burnet and Edward Stillingfleet', Journal of Ecclesiastical History, 44 (1993), 80-98
L. M. Principe, 'Virtuous romance and romantic virtuoso: the shaping of Robert Boyle's literary style', Journal of the History of Ideas (1995), 377-97
L. M. Principe, 'Newly discovered Boyle documents in the Royal Society's archive: alchemical tracts and his student notebook', Notes and Records of the Royal Society, 49 (1995), 57-70
L. M. Principe, 'Style and thought of the early Boyle: discovery of the 1648 manuscript of Seraphic love', Isis, 85 (1994), 247-60
J. T. Harwood, ed., The early essays and ethics of Robert Boyle (1991)
N. Canny, The upstart earl: a study of the social and mental world of Richard Boyle, first earl of Cork, 1566-1643 (1982)
A. Clericuzio, 'A redefinition of Boyle's chemistry and corpuscular philosophy', Annals of Science, 47 (1990), 561-89
C. Webster, The great instauration: science, medicine and reform, 1626-1660 (1975)
R. G. Frank, Harvey and the Oxford physiologists: a study of scientific ideas and social interaction (1980)
M. Boas, 'An early version of Boyle's Sceptical Chymist', Isis, 45 (1954), 153-68
R. M. Sargent, The diffident naturalist: Robert Boyle and the philosophy of experiment (1995)
S. Shapin and S. Schaffer, Leviathan and the air-pump: Hobbes, Boyle and the experimental life (1985)
T. Birch, The history of the Royal Society of London, 4 vols. (1756-7)
A brief account of Mr Valentine Greatrakes and divers of the strange cures by him lately performed (1666)
M. B. Hall, 'Acid and alcali in seventeenth-century chemistry', Archives Internationales d'Histoire des Sciences, 34 (1956), 13-28
R. E. W. Maddison, 'Robert Boyle and the Irish Bible', Bulletin of the John Rylands Library, 41 (1958), 81-101
A. Chalmers, 'The lack of excellency of Boyle's mechanical philosophy', Studies in the History and Philosophy of Science, 24 (1993), 541-64
M. Hunter, 'The reluctant philanthropist: Robert Boyle and the "Communication of secrets and receits in physick"', Religio medici: medicine and religion in seventeenth-century England, ed. O. P. Grell and A. Cunningham (1996), 247-272
M. Hunter, 'Boyle versus the Galenists: a suppressed critique of seventeenth-century medical practice and its significance', Medical History, 47 (1997), 322-61
L. M. Principe, The aspiring adept: Robert Boyle and his alchemical quest (1998)
J. W. Wojcik, Robert Boyle and the limits of reason (1997)
M. Hunter, Robert Boyle (1627-91): scrupulosity and science (2000)

BL, Birch papers
BL, Sloane papers
Chatsworth House, Derbyshire, corresp., accounts and papers
GL, corresp. with commissioners of New England
NL Ire., Orrery papers, letters and papers
NL Ire., Ormonde papers
Queen's College, Oxford, Barlow papers
RS, letters to Henry Oldenbury
University of Sheffield, Hartlib papers

W. Faithorne, line engraving, c.1659, BM, NPG
attrib. J. Riley, oils, 1682, RS
J. Smith, mezzotint, 1689 (after J. Kerseboom), BM, NPG
J. Smith, mezzotint, 1689, BM, NPG
J. Kerseboom, oils, 1689-1690, RS [see illus.]
C. R. Berch, medal, 1729 (after ivory medallion by J. Cavalier, 1690)
J. M. Rysbrack, marble bust, 1733, Royal Collection
W. Faithorne, portrait, AM Oxf.
J. Kerseboom, oils, other versions, NPG; Hardwick Hall, Derbyshire
sculpture (as a child), St Patrick's Cathedral, Dublin, tomb of the first earl of Cork

Wealth at death  
£10,000: Maddison, Life, 198

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