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

The senses deceive from time to time, and it is prudent never to trust wholly those who have deceived us even once.

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

Wonder is the first of all the passions.

Desire awakens only to things that are thought possible.

Sensations are nothing but confused modes of thinking.

[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.