Speculations apparently the most unprofitable have almost invariably been those from which the greatest practical applications have emanated.

There is a gentle, but perfectly irresistible coercion in a habit of reading well directed, over the whole tenor of a man's character and conduct, which is not the less effectual because it works insensibly, and because it is really the last thing he dreams of.

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.

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.

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.

It can hardly be pressed forcibly enough on the attention of the student of nature, that there is scarcely any natural phenomenon which can be fully and completely explained, in all its circumstances, without a union of several, perhaps of all, the sciences.

The novel, in its best form, I regard as one of the most powerful engines of civilization ever invented.