E3P52D
Demonstration — Part III
Latin
Simulatque objectum quod cum aliis vidimus, imaginamur, statim et aliorum recordamur (per propositionem 18 partis II, cujus etiam scholium vide) et sic ex unius contemplatione statim in contemplationem alterius incidimus. Atque eadem est ratio objecti quod nihil habere imaginamur nisi quod commune est pluribus. Nam eo ipso supponimus nos nihil in eo contemplari quod antea cum aliis non viderimus. Verum cum supponimus nos in objecto aliquo aliquid singulare quod antea nunquam vidimus, imaginari, nihil aliud dicimus quam quod mens dum illud objectum contemplatur, nullum aliud in se habeat in cujus contemplationem ex contemplatione illius incidere potest atque adeo ad illud solum contemplandum determinata est. Ergo objectum etc. Q.E.D.
English (Elwes 1883)
As soon as we conceive an object which we have seen in conjunction with others, we at once remember those others (II. xviii. and note), and thus we pass forthwith from the contemplation of one object to the contemplation of another object. And this is the case with the object, which we conceive to have no property that is not common to many. For we thereupon assume that we are regarding therein nothing, which we have not before seen in conjunction with other objects. But when we suppose that we conceive an object something special, which we have never seen before, we must needs say that the mind, while regarding that object, has in itself nothing which it can fall to regarding instead thereof; therefore it is determined to the contemplation of that object only. Therefore an object, &c. Q.E.D.
Modern English
As soon as we imagine an object that we have seen together with others, we immediately recall those others (E2P18), and so we pass at once from the contemplation of one thing to the contemplation of another. This is equally true of an object we conceive as having nothing but what is common to many things, because we thereby presuppose we perceive nothing in it that we have not seen together with other things before.
But when we suppose we imagine something particular in an object, something we have never seen before, we are saying nothing more than that the mind, while contemplating that object, has no other object in itself into whose contemplation it could pass; and so the mind is determined to contemplate that one object alone. Therefore that object, etc. Q.E.D.