“All known living bodies are sharply divided into two special kingdoms, based upon the essential differences which distinguish animals from plants, and in spite of what has been said, I am convinced that these two kingdoms do not really merge into one another at any point.”

The form follows the function.

It is not always the magnitude of the differences observed between species that must determine specific distinctions, but the constant preservation of those differences in reproduction.

It is not enough to discover and prove a useful truth previously unknown, but that it is necessary also to be able to propagate it and get it recognized.

All knowledge that is not the real product of observation, or of consequences deduced from observation, is entirely groundless and illusory.

Habits form a second nature.

What nature does in the course of long periods we do every day when we suddenly change the environment in which some species of living plant is situated.

It is not the organs-that is, the character and form of the animal’s bodily parts-that have given rise to its habits and particular structures. It is the habits and manner of life and the conditions in which its ancestors lived that have in the course of time fashioned its bodily form, its organs and qualities.

To me, health is a balanced mind. A balanced mind knows how to get enough rest, how to eat properly, how to exercise. I have come out as just a balanced human being, and I don’t know anything finer than that.

I’ve been known to make out with girls from time to time. Couple drinks involved, you know, it’s fun. And who knows, maybe it’ll go further someday.

What is known can’t jerk us around unwittingly. Before anything can be resolved, the implicit must be made into the explicit.

Successful people decide how they are going to live; they are not victims of circumstance. In good times or bad times, they know where they are going and they know that they are going to get there.

How do I know it was meant to happen this way? Because it did.

I also readily admit that there are animals, taken in the ordinary sense, that are incomparably larger than those we know of, and I have sometimes said in jest that there might be a system like ours which is the pocketwatch of some enormous giant.

It’s funny when people say, ‘I don’t think Julia likes me.’ Honey, if I don’t like you, you’re going to know about it.

Nothing you believe is true. To know this is freedom.