There is no man, however wise, who has not at some period of his youth said things, or even lived in a way which was so unpleasant to him in later life that he would gladly, if he could, expunge it from his memory. But he shouldn't regret this entirely, because he cannot be certain that he has indeed become a wise man--so far as any of us can be wise--unless he has passed through all the fatous or unwholesome incarnations by which that ultimate stage must be reached. . . .
We cannot be taught wisdom, we have to discover it for ourselves by a journey which no one can undertake for us, an effort which no one can spare us.
--Marcel Proust (How Proust Can Change Your Life, Alain de Botton, p. 67)