Full Idea
As reason makes no demands contrary to nature, it demands that every man should love himself, should seek that which is useful to him.
Gist of Idea
Reason demands nothing contrary to nature, and so it demands self-love
Source
Baruch de Spinoza (The Ethics [1675], IV Pr 18)
Book Reference
Spinoza,Benedict de: 'Ethics, Improvement of Understanding, Letters', ed/tr. Elwes,R [Dover 1955], p.201
A Reaction
Maybe nature seems to demand self-love, but I don't see why reason should demand it, only why reason should not deny it. There is no point in denying something unavoidable. However, if we don't love ourselves, no one else is likely to.