Desire

'If I find in myself a desire which no experience in the world can satisfy, the most probable explanation is that I was made for another world. If none of my earthly pleasures satisfy it, that does not prove that the universe is a fraud. Probably earthly pleasures were never meant to satisfy it, but only to arouse it, to suggest the real thing. If that be so, I must take care, on the one hand, never to despise, or to be unthankful for, these earthly blessings, on the other hand, never to mistake them for
something else of which they are only a kind of copy, or echo, or vestige. I must keep alive in myself the desire for my true country, which I shall not find till after death; I must never let it get snowed under or turned aside: I must make it the main focus of life to pass on to that country and to help others do the same.'

(CS Lewis Mere Christianity)