It is contrary to reasoning to say that there is a vacuum or space in which there is absolutely nothing.

If ... it is not in my power to arrive at the knowledge of any truth, I may at least do what is in my power, namely, suspend judgement.

[About Pierre de Fermat] It cannot be denied that he has had many exceptional ideas, and that he is a highly intelligent man. For my part, however, I have always been taught to take a broad overview of things, in order to be able to deduce from them general rules, which might be applicable elsewhere.

I am thinking, therefore I exist. (...) I was a substance whose whole essence or nature is solely to think, and which does not require any place, or depend on any material thing, in order to exist. Accordingly this 'I' - that is, the soul by which I am what I am - is entirely distinct from the body, and indeed is easier to know than the body, and would not fail to be whatever it is, even if the body did not exist.

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

It is to the body alone that we should attribute everything that can be observed in us to oppose our reason.

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