Sehnsucht - A deep-seated longing for joy: "that central music in every pure experience"; it may stab you but once you scrutnize that joy it becomes elusive. - An unatainable extasy which all your life has hovered just beyond the grasp of your conciousness.

The great breakthrough came when Lewis learned to discern between the desire for joy and the desire for that of which joy was the desiring. As long as you seek joy it evades you, but when you seek God, you find joy.

Knox Chamblin. Class notes from C.S. LEWIS. AN ELECTIVE IN THEOLOGY.