Man needs to know but little more than a lobster in order to catch him in his traps.

The voice of nature is always encouraging.

Let us not underrate the value of a fact; it will one day flower in a truth. It is astonishing how few facts of importance are added in a century to the natural history of any animal. The natural history of man himself is still being gradually written.

As for my own business, even that kind of surveying which I could do with most satisfaction my employers do not want. They would prefer that I should do my work coarsely and not too well, ay, not well enough. When I observe that there are different ways of surveying, my employer commonly asks which will give him the most land, not which is most correct.

It's not enough to be busy.

The fruits eaten temperately need not make us ashamed of our appetites, nor interrupt the worthiest pursuits. But put an extra condiment into your dish, and it will poison you.

As a man thinks of himself, so he is.