ii.), and to this extent only is always necessarily in harmony with the nature of another man (by the last Prop.); wherefore among individual things nothing is more useful to man, than a man who lives in obedience to reason.

Q.E.D.
Corollary II .-- As every man seeks most that which is useful to him, so are men most useful one to another.

For the more a man seeks what is useful to him and endeavours to preserve himself, the more is he endowed with virtue (IV.

xx.), or, what is the same thing (IV.Def.

viii.), the more is he endowed with power to act according to the laws of his own nature, that is to live in obedience to reason.