…the greater objective (representative) perfection there is in our idea of a thing, the greater also must be the perfection of its cause.
Some years ago I was struck by the large number of falsehoods that I had accepted as true in my childhood, and by the highly doubtful nature of the whole edifice that I had subsequently based on them. I realized that it was necessary, once in the course of my life, to demolish everything completely and start again right from the foundations if I wanted to establish anything at all in the sciences that was stable and likely to last.
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.
Except our own thoughts, there is nothing absolutely in our power.
I suppose therefore that all things I see are illusions; I believe that nothing has ever existed of everything my lying memory tells me. I think I have no senses. I believe that body, shape, extension, motion, location are functions. What is there then that can be taken as true? Perhaps only this one thing, that nothing at all is certain.
Clearly divine grace and natural knowledge never diminish liberty, but rather increase and strengthen it.
Each problem that I solved became a rule, which served afterwards to solve other problems.
Common sense is the most widely shared commodity in the world, for every man is convinced that he is well supplied with it.
The senses deceive from time to time, and it is prudent never to trust wholly those who have deceived us even once.
I desire to live in peace and to continue the life I have begun under the motto ‘to live well you must live unseen
I fully recognize that all certainty and truth in science depend only on a knowledge of the true God, so much so that, before I knew Him, I could have no perfect knowledge of anything else. But now I am able to understand innumerable things completely and clearly, about both God Himself and other intellectual matters, as well as about all those things in corporeal nature that are objects of study in pure mathematics.