E2P48D
Demonstration — Part II
Latin
Mens certus et determinatus modus cogitandi est (per propositionem 11 hujus) adeoque (per corollarium II propositionis 17 partis I) suarum actionum non potest esse causa libera sive absolutam facultatem volendi et nolendi habere non potest sed ad hoc vel illud volendum (per propositionem 28 partis I) determinari debet a causa quæ etiam ab alia determinata est et hæc iterum ab alia etc. Q.E.D.
English (Elwes 1883)
The mind is a fixed and definite mode of thought (II. xi.), therefore it cannot be the free cause of its actions (I. xvii. Coroll. ii.); in other words, it cannot have an absolute faculty of positive or negative volition; but (by I. xxviii.) it must be determined by a cause, which has also been determined by another cause, and this last by another, &c. Q.E.D.
Modern English
The mind is a certain and determinate mode of thinking (E2P11), and so (E1P17C2) it cannot be the free cause of its own actions and therefore cannot have an absolute faculty of willing and not-willing. It must be determined to will this or that (E1P28) by a cause that is itself determined by another cause, and that one by yet another, and so on. Q.E.D.