The books or the music in which we thought the beauty was located will betray us if we trust them; it was not in them, it only came through them, and what came through them was longing. These things—the beauty, the memory of our own past—are good images of what we really desire; but if they are mistaken for the thing itself they turn into dumb idols, breaking the hearts of their worshipers. For they are not the thing itself; they are only the scent of a flower we have not found, the echo of a tune we have not heard, news from a country we have never yet visited" (Lewis, "Weight of Glory").
Lewis, C. S. "The Weight of Glory." Mark Verber's Links to Christian Information. http://www.verber.com/mark/xian/weight-of-glory.pdf