Common sense is the most widely shared commodity in the world, for every man is convinced that he is well supplied with it.

To be wrong is nothing unless you continue remembering it.

The greatest wisdom consists in knowing one's own follies.

In order to improve the mind, we ought less to learn than to contemplate.

Except our own thoughts, there is nothing absolutely in our power.

The first precept was never to accept a thing as true until I knew it as such without a single doubt.

I am accustomed to sleep and in my dreams to imagine the same things that lunatics imagine when awake.

We do not describe the world we see, we see the world we can describe.

To know what people really think, pay regard to what they do, rather than what they say.

Travelling is almost like talking with men of other centuries.

Common sense is the most widely shared commodity in the world, for every man is convinced that he is well supplied with it.

The senses deceive from time to time, and it is prudent never to trust wholly those who have deceived us even once.

It is not enough to understand, you must also act.

The mind cannot comprehend the universe; the universe is too large.

It is only prudent never to place complete confidence in that by which we have even once been deceived.

Perfect numbers, like perfect men, are very rare.

The reading of all good books is like a conversation with the finest minds of past centuries.

Divide each difficulty into as many parts as is feasible and necessary to resolve it.

When you deal with nonfiction you deal with human characters.