"Among animals, some learn to speak and sing; they remember tunes, and strike the notes as exactly as a musician. Others, for instance the ape, show more intelligence... would it be absolutely impossible to teach the ape a language? I do not think so."

“The mind, like the body, has its contagious diseases and its scurvy. ...e catch everything from those with whom we come in contact; their gestures, their accent, etc.”

“A mere nothing, a tiny fibre, something that could never be found by the most delicate anatomy, would have made of Erasmus and Fontenelle two idiots, and Fontenelle himself speaks of this very fact in one of his best dialogues.”

“There comes up another difficulty which more nearly concerns our vanity: namely, the impossibility of our conceiving this property as a dependence or attribute of matter.”

“The ancients, persuaded that there is no body without a moving force, regarded the substance of bodies as composed of two primitive attributes. It was held that, through one of these attributes, this substance has the capacity for moving and, through the other, the capacity for being moved.”

“an... whatever the origin of his soul, if it is pure, noble, and lofty, it is a beautiful soul which dignifies the man endowed with it.”

“verything is the work of imagination, and... all the faculties of the soul can be correctly reduced to pure imagination...”