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

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.

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

Common sense is the most fairly distributed thing in the world, for each one thinks he is so well-endowed with it that even those who are hardest to satisfy in all other matters are not in the habit of desiring more of it than they already have.

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

I think; therefore I am.

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

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

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

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

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

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

I am indeed amazed when I consider how weak my mind is and how prone to error.

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

Illusory joy is often worth more than genuine sorrow.

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

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.

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

Travelling is almost like talking with those of other centuries.

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

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

Everything is self-evident.

When it is not in our power to follow what is true, we ought to follow what is most probable.

Perfect numbers like perfect men are very rare.

The greatest minds are capable of the greatest vices as well as of the greatest virtues.

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

The two operations of our understanding, intuition and deduction, on which alone we have said we must rely in the acquisition of knowledge.

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

Nothing is more fairly distributed than common sense: no one thinks he needs more of it than he already has.

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

So blind is the curiosity by which mortals are possessed that they often conduct their minds along unexplored routes having no reason to hope for success but merely being willing to risk the experiment of finding whether the truth they seek lies there.

Any community that gets its laughs by pretending to be idiots will eventually be flooded by actual idiots who mistakenly believe that theyre in good company.

Doubt is the origin of wisdom.

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

When it is not in our power to follow what is true we ought to follow what is most probable.

There is nothing so far removed from us to be beyond our reach or so far hidden that we cannot discover it.

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

The principal effect of the passions is that they incite and persuade the mind to will the events for which they prepared the body.

The principal use of prudence, of self-control, is that it teaches us to be masters of our passions, and to so control and guide them that the evils which they cause are quite bearable, and that we even derive joy from them all.

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 they reveal to us none but the best of their thoughts.

What does reason know? Reason only knows what it has succeeded in learning.

Reason is the only thing that makes us men, and distinguishes us from the beasts.

In order to seek truth, it is necessary once in the course of our life to doubt, as far as possible, of all things.

Wonder is the first of all passion.

There is no rational reason to doubt that the universe has existed indefinitely, for an infinite time. It is only myth that attempts to say how the universe came to be, either four thousand or twenty billion years ago.

When in doubt wear red.

As I think through the issue of funding the rebuilding of Iraq, I think about the analogy of a bankruptcy proceeding. There is no doubt that Iraq as a country is bankrupt.

After having dispatched a meal, I went ashore, and found no habitation save a single house, and that without an occupant; we had no doubt that the people had fled in terror at our approach, as the house was completely furnished.

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.