I doubt, therefore I think; I think therefore I am.

Dubito ergo cogito; cogito ergo sum.

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.

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.

I think; therefore I am

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

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

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

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

Traveling is almost like talking with men of other centuries.

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