Sorrow is God's plowshare that turns up and subsoils the depths of the soul, that it may yield richer harvests. If we had never fallen, or were in a glorified state, then the strong torrents of Divine joy would be the normal force to open up all our souls' capacities; but in a fallen world, sorrow, with despair taken out of it, is the chosen power to reveal ourselves to ourselves. Hence it is sorrow that makes us think deeply, long, and soberly.