One cannot help feeling in this passage that the poet hints that these prophecies of Circe have some connection with what Ulysses imparts to her concerning Hades. Indeed she repeats what Tiresias had already foretold in reference to the Oxen of the Sun--a matter which she probably heard from Ulysses. Cannot the other two adventures be derived in a general way from the experiences of the Underworld? The Past seems here to furnish the groundwork for the predictions of the Future, and Circe, knowing what has been in the pure forms of the supersensible, becomes the voice of what is to be. 1. First come the Sirens, whom Ulysses will have to meet again, as he has often met them before. Indeed Circe herself was once a Siren, a charmer through the senses. The present Sirens are singers, and entice to destruction through the sense of hearing, inasmuch as "heaps of bones lie about them," evidently the skeletons of persons who have perished through their seductive song. Pass them the man must; what is to be done? He will have somehow to guard against his sensuous nature and keep it from destroying itself. Yet on the other hand he must enjoy, which is his right in this world of sensations; each good music must be heard. So Circe tells of the scheme of putting wax into his companions' ears, while he is bound to the mast. Already Tiresias warned Ulysses in the Underworld to hold his appetite in check and that of his companions, if he wished to return home. This warning Circe now repeats, indeed she repeats in a new mythical form her own experience, for she, the Siren, has also been met by Ulysses and mastered. Yet these later charmers seem to have been more dangerous. When they are passed, a new peril rises of necessity. 2. Next we behold an image, or rather two sets of images, of the grand dualism of existence. That escape from the Sirens is really no solution of the problem, it is external and leaves the man still unfree, still subject to his senses. There must be somehow an inner control through the understanding, an intellectual subordination. But just here trouble springs up again. The mind has two sides to it, and is certain to fall into self-opposition. Two are the ways after parting from the Sirens, says Circe: "I shall tell thee of both." One way is by the Plangctae (rocks which clasp together); here no bird can fly through without getting caught, even the doves of Zeus pay the penalty. "No ship of men, having gone thither, has ever escaped"--except the God-directed Argo: surely a sufficient warning. Then the second way also leads to two rocks, but of a different kind; at their bases in the sea are found Scylla, the monstrous sea-bitch, on one side, and Charybdis, the yawning maelstrom, on the other; between them Ulysses must pass with his ship and companions.