Knowledge has two extremes. The first is the pure natural ignorance in which all men find themselves at birth. The other extreme is that reached by great minds, who, having run through all that men can know, find they know nothing, and come back again to that same natural ignorance from which they set out; this is a learned ignorance which is conscious of itself.

All human evil comes from a single cause, man's inability to sit still in a room.

Those who are accustomed to judge by feeling do not understand the process of reasoning, because they want to comprehend at a glance and are not used to seeking for first principles. Those, on the other hand, who are accustomed to reason from first principles do not understand matters of feeling at all, because they look for first principles and are unable to comprehend at a glance.

Let us now speak according to natural lights. If there is a God, He is infinitely incomprehensible. . . . We are then incapable of knowing of either what He is or if He is. . . .

I have spent much time in the study of the abstract sciences; but the paucity of persons with whom you can communicate on such subjects disgusted me with them. When I began to study man, I saw that these abstract sciences are not suited to him, and that in diving into them, I wandered farther from my real object than those who knew them not, and I forgave them for not having attended to these things. I expected then, however, that I should find some companions in the study of man, since it was so specifically a duty. I was in error. There are fewer students of man than of geometry.

There is enough light for those who only desire to see, and enough obscurity for those who have a contrary disposition

We do not worry about being respected in towns through which we pass. But if we are going to remain in one for a certain time, we do worry. How long does this time have to be?