"The soul truly exists."

"I always wanted to learn to distinguish the true from the false, in order to see clearly in my actions and to walk with confidence in this life."

"I desire to live, and to continue the studies I have begun, but I have not found anyone who could tell me where to go."

"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, the kno…"

"The whole of philosophy is like a tree, whose roots are metaphysics, whose trunk is physics, and whose branches are all the other sciences."