I hope that posterity will judge me kindly, not only as to the things which I have explained, but also to those which I have intentionally omitted so as to leave to others the pleasure of discovery.

Illusory joy is often worth more than genuine sorrow.

There is nothing so strange and so unbelievable that it has not been said by one philosopher or another.

One cannot conceive anything so strange and so implausible that it has not already been said by one philosopher or another.

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

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

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

An optimist may see a light where there is none, but why must the pessimist always run to blow it out?

I think; therefore I am.

You just keep pushing. You just keep pushing. I made every mistake that could be made. But I just kept pushing.

If you would be a real seeker after truth, it is necessary that at least once in your life you doubt, as far as possible, all things.

Whenever anyone has offended me, I try to raise my soul so high that the offense cannot reach it.

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

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

A state is better governed which has few laws, and those laws strictly observed.

Perfect numbers like perfect men are very rare.

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

Each problem that I solved became a rule, which served afterwards to solve other problems.

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

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