From Friedrich Nietzsche, Human, All Too Human, Part II:
58. Dangerous Books. —A man says: “Judging from my own case, I find that this book is harmful.” Let him but wait, and perhaps one day he will confess that the book did him a great service by thrusting forward and bringing to light the hidden disease of his soul.—Altered opinions alter not at all (or very little) the character of a man: but they illuminate individual facets of his personality, which hitherto, in another constellation of opinions, had remained dark and unrecognisable.
