I trust and believe that the time spent in this voyage ... will produce its full worth in Natural History; and it appears to me the doing what little we can to increase the general stock of knowledge is as respectable an object of life, as one can in any likelihood pursue.

In the distant future I see open fields for far more important researches. Psychology will be based on a new foundation, that of the necessary acquirement of each mental power and capacity by gradation. Light will be thrown on the origin of man and his history.

I shall always feel respect for every one who has written a book, let it be what it may, for I had no idea of the trouble which trying to write common English could cost one—And alas there yet remains the worst part of all correcting the press.

Daily it is forced home on the mind of the biologist that nothing, not even the wind that blows, is so unstable as the level of the crust of this earth.

The instruction at Edinburgh was altogether by lectures, and these were intolerably dull, with the exception of those on chemistry.

It is always advisable to perceive clearly our ignorance.

It is certain that there may be extraordinary mental activity with an extremely small absolute mass of nervous matter: thus the wonderfully diversified instincts, mental powers, and affections of ants are notorious, yet their cerebral ganglia are not so large as the quarter of a small pin's head. Under this point of view, the brain of an ant is one of the most marvelous atoms of matter in the world, perhaps more so than the brain of a man.