About death, I go through different moods, but the times when I can desire it are never, I think, those when this world seems harshest. On the contrary, it is just when there seems to be most of Heaven already here that I come nearest to longing for the patria. It is the bright frontispiece [which] whets one to read the story itself. All joy (as distinct from mere pleasure, still more amusement) emphasises our pilgrim status: always reminds, beckons, awakes desire. Our best havings are wantings.
The Collected Letters of C.S. Lewis, Volume III
“Emphasises our pilgrim status” because our true joy is not to be found here below. A pilgrim is one who journeys to a holy place and we will only find true joy if (or when) our journey leads us to Heaven.