‘There is no such thing as a good influence. 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.
From The Picture of Dorian Gray, an 1891 philosophical novel by writer and playwright Oscar Wilde