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

For the very fact that my knowledge is increasing little by little is the most certain argument for its imperfection.

At last I will devote myself sincerely and without reservation to the general demolition of my opinions.

I had become aware, as early as my college days, that no opinion, however absurd and incredible can be imagined, that has not been held by one of the philosophers.

To know what people really think, pay attention to what they do, rather than what they say.

Let whoever can do so deceive me, he will never bring it about that I am nothing, so long as I continue to think I am something.

Am I so tied to a body and senses that I am incapable of existing without them?

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

Masked, I advance.

There is nothing more ancient than the truth.

For I found myself embarrassed with so many doubts and errors that it seemed to me that the effort to instruct myself had no effect other than the increasing discovery of my own ignorance

All that is necessary to right action is right judgment, and to the best action the most correct judgment.

I desire to live in peace and to continue the life I have begun under the motto ‘to live well you must live unseen’.

Truths are more likely to have been discovered by one man than by nation

I doubt, therefore I think, therefore I am.

But what then am I? A thing that thinks. What is that? A thing that doubts, understand, affirms, denies, wills, refuses, and that also imagines and senses.

The will determines itself; it should not be described as blind, any more than vision should be described as deaf.

Determine never to be idle. No person will have occasion to complain of the want of time, who never loses any. It is wonderful how much may be done, if we are always doing.

The things you think about determine the quality of your mind.

Not everybody can be famous but everybody can be great, because greatness is determined by service.

The direction in which education starts a man will determine his future life

One’s desire, not ability, determines success.

Someone else’s action should not determine your response.