Humankind's Longing for Paradise: Where does it come from?

A man’s physical hunger does not prove that man will get any bread; he may die of starvation on a raft in the Atlantic. But surely a man’s hunger does prove that he comes of a race which repairs its body by eating and inhabits a world where eatable substances exist. In the same way, though I do not believe (I wish I did) that my desire for Paradise proves that I shall enjoy it, I think it a pretty good indication that such a thing exists and that some men will (C.S. Lewis, The Weight of Glory, 32-33)