4p35c1.md (582B)
1 There is no individual thing in nature, which is 2 more useful to man, than a man who lives in obedience to reason. 3 For that thing is to man most useful, which is most in harmony 4 with his nature (IV. xxxi. Coroll.); that is, obviously, man. 5 But man acts absolutely according to the laws of his nature, when 6 he lives in obedience to reason (III. Def. ii.), and to this 7 extent only is always necessarily in harmony with the nature of 8 another man (by the last Prop.); wherefore among individual 9 things nothing is more useful to man, than a man who lives in 10 obedience to reason. Q.E.D. 11 12