It was my design to comprise in it all that I thought I knew of the nature of material objects, but fearing lest I should not be able to comprise all, I resolved to expound my opinions regarding light, to take the opportunity of adding something on the sun and the fixed stars, since light proceeds from them, on the heavens, since they transmit it, on the planets, comets, and earth, since they reflect it; on the bodies that are on the earth, since they are either coloured or transparent or luminous; and finally on man, since he is the spectator. I explained what the nature of light must be, and how in an instant of time it traverses the immense spaces of the heavens, and how from the planets it is reflected toward the earth. To this I added much respecting the substance, the situation, the motions, and the qualities of the heavens and stars. I came to speak of the earth, to show how its parts tend to its centre, how with water and air on its surface the disposition of the heavenly bodies, more especially the moon, must cause a flow and ebb, how the mountains, seas, fountains and rivers might naturally be formed, and the metals produced in the mines, and the plants grow in the fields, and I set forth all that pertains to the nature of fire, how it induces various colours upon different bodies, how it reduces some to a liquid state and hardens others, how it can convert bodies into ashes and smoke, and how from these ashes it forms glass. I passed to the description of animals and particularly to man. I gave the explication of the motion of the heart and arteries, - what must be the fabric of the nerves and muscles, what changes take place in the brain to produce waking, sleep, and dreams, how light, sounds, odours, tastes and heat impress it with different ideas, how hunger and thirst can impress it, what must be understood by the common sense, by the memory, by the imagination. I had after this described the soul, and showed that it could by no means be educed from the power of matter but that it must be expressly created.
I was not, however, disposed to conclude that this world had been created in the manner I described; for it is much more likely that God made it at the first such as it was to be. I spoke only of what would happen in a new world, if God were now to create somewhere matter sufficient to compose one, and were to agitate confusedly the parts so that there resulted a chaos, and after that allowed nature to act in accordance with the laws which He had established. I pointed out what are the laws of nature, and thereafter I showed how the greatest part of the matter in this chaos must in accordance with these laws arrange itself to present the appearance of the heavens, how some parts must compose an earth and some planets and comets, and others a sun and fixed stars.