Occurrences which according to received theories ought not to happen, are the facts which serve as clues to new discoveries
The stars are the land-marks of the universe.
To the natural philosopher, there is no natural object unimportant or trifling. From the least of Nature's works he may learn the greatest lessons.
A mind which has once imbibed a taste for scientific inquiry, and has learnt the habit of applying its principles readily to the cases which occur, has within itself an inexhaustible source of pure and exciting contemplations.
Every student who enters upon a scientific pursuit, especially if at a somewhat advanced period of life, will find not only that he has much to learn, but much also to unlearn.
Speculations apparently the most unprofitable have almost invariably been those from which the greatest practical applications have emanated.
Almost all the greatest discoveries in astronomy have resulted from what we have elsewhere termed Residual Phenomena, of a qualitative or numerical kind, of such portions of the numerical or quantitative results of observation as remain outstanding and unaccounted for, after subducting and allowing for all that would result from the strict application of known principles.