2p17cd.md (1138B)
1 When external bodies determine the fluid parts of the 2 human body, so that they often impinge on the softer parts, they 3 change the surface of the last named (Post. v.); hence (Ax. ii., 4 after the Coroll. of Lemma iii.) they are refracted therefrom in 5 a different manner from that which they followed before such 6 change; and, further, when afterwards they impinge on the new 7 surfaces by their own spontaneous movement, they will be 8 refracted in the same manner, as though they had been impelled 9 towards those surfaces by external bodies; consequently, they 10 will, while they continue to be thus refracted, affect the human 11 body in the same manner, whereof the mind (II. xii.) will again 12 take cognizance–that is (II. xvii.), the mind will again regard 13 the external body as present, and will do so, as often as the 14 fluid parts of the human body impinge on the aforesaid surfaces 15 by their own spontaneous motion. Wherefore, although the 16 external bodies, by which the human body has once been affected, 17 be no longer in existence, the mind will nevertheless regard them 18 as present, as often as this action of the body is repeated. 19 Q.E.D. 20 21