E3P53D
Demonstration — Part III
Latin
Homo se ipsum non cognoscit nisi per affectiones sui corporis earumque ideas (per propositiones 19 et 23 partis II). Cum ergo fit ut mens se ipsam possit contemplari, eo ipso ad majorem perfectionem transire hoc est (per scholium propositionis 11 hujus) lætitia affici supponitur et eo majore quo se suamque agendi potentiam distinctius imaginari potest. Q.E.D.
English (Elwes 1883)
A man does not know himself except through the modifications of his body, and the ideas thereof (II. xix. and xxiii.). When, therefore, the mind is able to contemplate itself, it is thereby assumed to pass to a greater perfection, or (III. xi. note) to feel pleasure; and the pleasure will be greater in proportion to the distinctness, wherewith it is able to conceive itself and its own power of activity. Q.E.D.
Modern English
A person knows himself only through the affections of his body and through their ideas (E2P19). When the mind is therefore able to contemplate itself, it is thereby assumed to pass to greater perfection, that is, (E3P11S), to be affected with joy. And the more distinctly it can imagine itself and its power of acting, the greater that joy will be. Q.E.D.