C. S. Lewis' breathtaking answer:
Let us construct a fable.
Let us picture a woman thrown into a dungeon. There she bears and rears a son. He grows up seeing nothing but the dungeon walls, the straw on the floor, and a little patch of the sky seen through the grating, which is too high up to show anything except sky.
This unfortunate woman was an artist, and when they imprisoned her she managed to bring with her a drawing pad and a box of pencils. As she never loses the hope of deliverance, she is constantly teaching her son about that outer world which he has never seen. She does it very largely by drawing him pictures. With her pencil she attempts to show him what fields, rivers, mountains, cities, and waves on a beach are like.
He is a dutiful boy and he does his best to believe her when she tells him that that outer world is far more interesting and glorious than anything in the dungeon. At times he succeeds. On the whole he gets on tolerably well until, one day, he says something that gives his mother pause. For a minute or two they are at cross-purposes. Finally it dawns on her that he has, all these years, lived under a misconception.
'But,' she gasps, 'you didn't think that the real world was full of lines drawn in lead pencil?'
'What?' says the boy. 'No pencil marks there?'
And instantly his whole notion of the outer world becomes a blank. For the lines, by which alone he was imagining it, have now been denied of it. He has no idea of that which will exclude and dispense with the lines, that of which the lines were merely a transposition--the waving treetops, the light dancing on the weir, the coloured three-dimensional realities which are not enclosed in lines but define their own shapes at every moment with a delicacy and multiplicity which no drawing could ever achieve. The child will get the idea that the real world is somehow less visible than his mother's pictures. In reality it lacks lines because it is incomparably more visible.
So with us. 'We know not what we shall be'; but we may be sure we shall be more, not less, than we were on earth. Our natural experiences (sensory, emotional, imaginative) are only like the drawing, like pencilled lines on flat paper. If they vanish in the risen life, they will vanish only as pencil lines from the real landscape, not as a candle flame that is put out but as a candle flame which becomes invisible because someone has pulled up the blind, thrown open the shutters, and let in the blaze of the risen sun.
--C. S. Lewis, 'Transposition,' in The Weight of Glory, 85-86