“Matter and mind have this in common, that certain superficial agitations of matter are expressed in our minds, superficially, in the form of sensations; and on the other hand, the mind, in order to act upon the body, must descend little by little toward matter and become spatialized. It follows that the intelligence, although turned toward external things, can still be exerted on things internal, provided that it does not claim to plunge too deeply.”
