E2P17D
Demonstration — Part II
Latin
Patet. Nam quamdiu corpus humanum sic affectum est tamdiu mens humana (per propositionem 12 hujus) hanc corporis affectionem contemplabitur hoc est (per propositionem præcedentem) ideam habebit modi actu existentis quæ naturam corporis externi involvit hoc est ideam quæ existentiam vel præsentiam naturæ corporis externi non secludit sed ponit adeoque mens (per corollarium I præcedentis) corpus externum ut actu existens vel ut præsens contemplabitur donec afficiatur etc. Q.E.D.
English (Elwes 1883)
This proposition is self--evident, for so long as the human body continues to be thus affected, so long will the human mind (II. xii.) regard this modification of the body--that is (by the last Prop.), it will have the idea of the mode as actually existing, and this idea involves the nature of the external body. In other words, it will have the idea which does not exclude, but postulates the existence or presence of the nature of the external body; therefore the mind (by II. xvi., Coroll. i.) will regard the external body as actually existing, until it is affected, &c. Q.E.D.
Modern English
This is evident. For as long as the human body is thus affected, the human mind (E2P12) will regard this affection of the body, that is, (E2P17), it will have the idea of a mode as actually existing, which involves the nature of the external body, that is, an idea that does not exclude but posits the existence or presence of that external body's nature. Therefore the mind (E2P16C1) will regard the external body as actually existing or as present to it, until it is affected otherwise. Q.E.D.