E3P59D
Demonstration — Part III
Latin
Omnes affectus ad cupiditatem, lætitiam vel tristitiam referuntur ut eorum quas dedimus definitiones ostendunt. Per tristitiam autem intelligimus quod mentis cogitandi potentia minuitur vel coercetur (per propositionem 11 hujus et ejus scholium) adeoque mens quatenus contristatur eatenus ejus intelligendi hoc est ejus agendi potentia (per propositionem 1 hujus) minuitur vel coercetur adeoque nulli tristitiæ affectus ad mentem referri possunt quatenus agit sed tantum affectus lætitiæ et cupiditatis qui (per propositionem præcedentem) eatenus etiam ad mentem referuntur. Q.E.D.
English (Elwes 1883)
All emotions can be referred to desire, pleasure, or pain, as their definitions, already given, show. Now by pain we mean that the mind's power of thinking is diminished or checked (III. xi. and note); therefore, in so far as the mind feels pain, its power of understanding, that is, of activity, is diminished or checked (III. i.); therefore, no painful emotions can be attributed to the mind in virtue of its being active, but only emotions of pleasure and desire, which (by the last Prop.) are attributable to the mind in that condition. Q.E.D.
Modern English
All affects are referred to desire, joy, or sadness, as the definitions given show. By sadness we understand that the mind's power of thinking is diminished or checked (E3P11). Therefore, insofar as the mind is saddened, its power of understanding, that is (E3P1), its power of acting, is diminished or checked. So no affects of sadness can be referred to the mind insofar as it acts. Only affects of joy and desire can, and these (E3P58) are also referred to the mind insofar as it acts. Q.E.D.