Rene Descartes

The long chains of simple and easy reasonings by means of which geometers are accustomed to reach the conclusions of their most difficult demonstrations, had led me to imagine that all things, to the knowledge of which man is capable, are mutually connected in the same way.

The soul truly exists.

To be able to live without fear, without anxiety, without sadness, and without any other passion which could disturb the tranquillity of the soul.

I have always taken the greatest pleasure in seeking out and acquiring knowledge.

I resolved to feign that all the perceptions I had ever received were no truer than the illusions of my dreams.