The soul, and its distinction from the body. The nature of ideas. The world in which our bodies live and which we look at is very different from the one we see.

THEODORE. Well then, my dear Aristes, since you wish it, I must tell you about my metaphysical visions. But to do so I must leave these enchanted places which delight our senses and which, by their variety, distract a mind like mine. Because I am extremely afraid of taking, for the immediate deliverances of inner truth, some of my prejudices or those obscure principles which owe their birth to the laws of the union of the soul and body; and because in these surroundings I cannot, as perhaps you can, silence a certain disturbing noise which throws confusion and turmoil into all my ideas; please, let us leave here. Let us withdraw to your study, in order to retreat into ourselves more easily. Let us attempt to have nothing prevent us each from consulting our common master, universal Reason. For it is inner truth that must govern our discussion. This is what must dictate to me what I should tell you and what you are to learn through me. In a word, it belongs to inner truth alone to judge and pronounce upon our differences. For today we think only of philosophizing: and although you submit perfectly to the authority of the church, you wish me to speak from the outset as if you refused to accept the truths of faith as principles of our knowledge.