4p35c2.md (621B)
1 As every man seeks most that which is useful to 2 him, so are men most useful one to another. For the more a man 3 seeks what is useful to him and endeavours to preserve himself, 4 the more is he endowed with virtue (IV. xx.), or, what is the 5 same thing (IV. Def. viii.), the more is he endowed with power to 6 act according to the laws of his own nature, that is to live in 7 obedience to reason. But men are most in natural harmony, when 8 they live in obedience to reason (by the last Prop.); therefore 9 (by the foregoing Coroll.) men will be most useful one to 10 another, when each seeks most that which is useful to him. 11 Q.E.D. 12 13