E5P41D
Demonstration — Part V
Latin
Primum et unicum virtutis seu recte vivendi rationis fundamentum (per corollarium propositionis 22 et per propositionem 24 partis IV) est suum utile quærere. Ad illa autem determinandum quæ ratio utilia esse dictat, nullam rationem habuimus mentis æternitatis quam demum in hac quinta parte novimus. Quamvis igitur tum temporis ignoraverimus mentem esse æternam, illa tamen quæ ad animositatem et generositatem referri ostendimus, prima habuimus atque adeo quamvis etiam nunc hoc ipsum ignoraremus, eadem tamen præscripta prima haberemus. Q.E.D.
English (Elwes 1883)
The first and only foundation of virtue, or the rule of right living is (IV. xxii. Coroll. and xxiv.) seeking one's own true interest. Now, while we determined what reason prescribes as useful, we took no account of the mind's eternity, which has only become known to us in this Fifth Part. Although we were ignorant at that time that the mind is eternal, we nevertheless stated that the qualities attributable to courage and high--mindedness are of primary importance. Therefore, even if we were still ignorant of this doctrine, we should yet put the aforesaid precepts of reason in the first place. Q.E.D.
Modern English
The first and only foundation of virtue, or of the rule of right living, is seeking one's own advantage (E4P22C)(E4P24). In determining what reason prescribes as useful, we took no account of the mind's eternity, which we came to know only in this fifth part. Although we were ignorant of the mind's eternity at that time, we still placed first those things we showed to belong to courage and generosity. So even if we were now ignorant of this as well, we would still place those same precepts first. Q.E.D.