Cogito ergo sum. (I think; therefore I am. )

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

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

It is not enough to have a good mind. The main thing is to use it well.

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

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

The reading of all good books is indeed like a conversation with the noblest men of past centuries who were the authors of them, nay a carefully studied conversation, in which t ...