Because to influence a person is to give him one’s own soul. He does not think his natural thoughts, or burn with his natural passions. His virtues are not real to him. His sins, if there are such things as sins, are borrowed. He becomes an echo of some one else’s music, an actor of a part that has not been written for him. The aim of life is self-development. To realize one’s nature perfectly — that is what each of us is here for. People are afraid of themselves, nowadays. They have forgotten the highest of all duties, the duty that one owes to oneself. Of course they are charitable. They feed the hungry, and clothe the beggar. But their own souls starve, and are naked. Courage has gone out of our race. Perhaps we never really had it. The terror of society, which is the basis of morals, the terror of God, which is the secret of religion — these are the two things that govern us.
Lord Henry Wotton, from Oscar Wilde’s The Picture of Dorian Gray (1890)