 Descartes formulates no distinction of P/SQs but familiar doctrines to which he is committed point to one. He maintains that his mechanist theory of matter and motion can explain everything in the corporeal world (CSM 1.285; AT  8.323).[2]  He holds that bodies and minds are substances each of which can exist independently of the other (CSM 2.54; AT 7.78). According to him, knowledge of continuous extension, and the sizes, figures, positions, and local motions of its parts, is innate in the human intellect, or mind (CSM 2.44; AT 7.63). By contrast, we know SQs only with aid of the body (CSM 1.217; AT 8.33–4). The Cartesian P/SQ distinction implicit in these doctrines has three roots: