“With me, everything turns into mathematics.”

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

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

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

I think; therefore I am.

To live without philosophizing is in truth the same as keeping the eyes closed without attempting to open them.

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.

Bad books engender bad habits, but bad habits engender good books.

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

Nothing is made from nothing.

To think? That’s it. It is thought. This alone cannot be detached from me. I am, I exist; that is certain.

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

To live well is to live concealed.

It is best not to go on for great quest for truth , it will only make you miserable

The dreams we imagine when we are asleep should not in any way make us doubt the truth of the thoughts we have when we are awake.

The destruction of the foundations necessarily brings down the whole edifice.

For to be possessed of a vigorous mind is not enough; the prime requisite is rightly to apply it.