E3P18D
Demonstration — Part III
Latin
Quamdiu homo rei alicujus imagine affectus est, rem ut præsentem tametsi non existat, contemplabitur (per propositionem 17 partis II cum ejusdem corollario) nec ipsam ut præteritam aut futuram imaginatur nisi quatenus ejus imago juncta est imagini temporis præteriti aut futuri (vide scholium propositionis 44 partis II). Quare rei imago in se sola considerata eadem est sive ad tempus futurum vel præteritum sive ad præsens referatur hoc est (per corollarium II propositionis 16 partis II) corporis constitutio seu affectus idem est sive imago sit rei præteritæ vel futuræ sive præsentis atque adeo affectus lætitiæ et tristitiæ idem est sive imago sit rei præteritæ aut futuræ sive præsentis. Q.E.D.
English (Elwes 1883)
So long as a man is affected by the image of anything, he will regard that thing as present, even though it be non--existent (II. xvii. and Coroll.), he will not conceive it as past or future, except in so far as its image is joined to the image of time past or future (II. xliv. note). Wherefore the image of a thing, regarded in itself alone, is identical, whether it be referred to time past, time future, or time present; that is (II. xvi. Coroll.), the disposition or emotion of the body is identical, whether the image be of a thing past, future, or present. Thus the emotion of pleasure or pain is the same, whether the image be of a thing past or future. Q.E.D.
Modern English
As long as a person is affected by the image of anything, they regard that thing as present even if it does not exist (E2P17); they do not imagine it as past or future except insofar as its image is joined to an image of past or future time (E2P44S). The image of a thing, considered in itself alone, is therefore the same whether it refers to future, past, or present time. That is (E2P16C2), the bodily constitution, the affect, is the same whether the image is of a past, future, or present thing. Consequently the affect of joy or sadness is the same whether the image is of a past, future, or present thing. Q.E.D.