But in my opinion, all things in nature occur mathematically.

Sensations are nothing but confused modes of thinking.

Travelling is almost like talking with those of other centuries.

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

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.

God alone is the author of all the motions in the world.

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.