Whatever you put serious effort into, you naturally love. Do people put serious effort into bad things? No way. Do they put effort into things that don't matter to them at all? No, not those either. So people only put real effort into things that are good. And if they put effort into things, they love those things too. If you understand what's truly good, you can know how to love properly. But if you can't tell good from bad, or good and bad from neutral things, how can you have the power to love? Real love belongs only to the wise.
What a man applies himself to earnestly, that he naturally loves. Do men then apply themselves earnestly to the things which are bad? By no means. Well, do they apply themselves to things which in no way concern themselves? Not to these either. It remains then that they employ themselves earnestly only about things which are good; and if they are earnestly employed about things, they love such things also. Whoever then understands what is good can also know how to love; but he who cannot distinguish good from bad, and things which are neither good nor bad from both, how can he possess the power of loving? To love, then, is only in the power of the wise.