Every idea is an incitement. It offers itself for belief, and if believed it is acted on unless some other belief outweighs it or some failure of energy stifles the movement at its birth. The only difference between the expression of an opinion and an incitement is the speaker's enthusiasm for the result.

Longevity is having a chronic disease - and taking care of it.

There is one gratification an old author can afford a certain class of critics; that namely, of comparing him as he is with what he was. It is a pleasure to mediocrity to have its superiors brought within range.

In order to know whether a human being is young or old, offer it food of different kinds at short intervals. If young, it will eat anything at any hour of the day or night.

Any new formula which suddenly emerges in our consciousness has its roots in long trains of thought; it is virtually old when it first makes its appearance among the recognized growths of our intellect.

I despise making the most of one's time. Half of the pleasures of life consist of the opportunities one has neglected.

I dare say that I have worked off my fundamental formula on you that the chief end of man is to frame general propositions and that no general proposition is worth a damn.