I can still recall vividly how Freud said to me, 'My dear Jung, promise me never to abandon the sexual theory. That is the most essential thing of all. You see, we must make a dogma of it, an unshakable bulwark' ... In some astonishment I asked him, 'A bulwark-against what?' To which he replied, 'Against the black tide of mud'—and here he hesitated for a moment, then added—'of occultism'.