Intelligence is quickness to apprehend as distinct form ability, which is capacity to act wisely on the thing apprehended.

We think in generalities, but we live in detail.

Mathematics, in its widest significance, is the development of all types of formal, necessary, deductive reasoning.

There is no more common error than to assume that, because prolonged and accurate mathematical calculations have been made, the application of the result to some fact of nature is absolutely certain.

The vitality of thought is in adventure. Ideas won't keep. Something must be done about them. When the idea is new, its custodians have fervor, live for it, and if need be, die for it.

In England if something goes wrong--say, if one finds a skunk in the garden--he writes to the family solicitor, who proceeds to take the proper measures; whereas in America, you telephone the fire department. Each satisfies a characteristic need; in the English, love of order and legalistic procedure; and here in America, what you like is something vivid, and red, and swift.

There is a technique, a knack, for thinking, just as there is for doing other things. You are not wholly at the mercy of your thoughts, any more than they are you. They are a machine you can learn to operate.