Even on funeral monuments the notion of the Siren as either soul or Death-Angel is more and more obscured by her potency as sweet singer. Once, however, when she appears in philosophy, there is at least a haunting remembrance that she is a soul who sings to souls. In the cosmography with which he ends the _Republic_, Plato[525] thus writes: ‘The spindle turns on the knees of Ananke, and on the upper surface of each sphere is perched a Siren, who goes round with them hymning a single tone. The eight together form one Harmony.’ Commentators explain that the Sirens are chosen because they are sweet singers, but then, if music be all, why is it the evil Sirens and not the good Muses who chant the music of the spheres? Plutarch[526] felt the difficulty. In his _Symposiacs_ he makes one of the guests say: ‘Plato is absurd in committing the eternal and divine revolutions not to the Muses but to the Sirens; demons who are by no means either benevolent or in themselves good.’ Another guest, Ammonius, attempts to justify the choice of the Sirens by giving to them in Homer a mystical significance. ‘Even Homer,’ he says, ‘means by their music not a power dangerous and destructive to man, but rather a power that inspires in the souls that go from Hence Thither, and wander about after death, a love for things heavenly and divine and a forgetfulness of things mortal, and thereby holds them enchanted by singing. Even here,’ he goes on to say, ‘a dim murmur of that music reaches us, rousing reminiscence.’ It is not to be for a moment supposed that Homer’s Sirens had really any such mystical content. But, given that they have the bird-form of souls, that they ‘know all things,’ are sweet singers and dwellers in Hades, and they lie ready to the hand of the mystic. Proclus[527] in his commentary on the _Republic_ says, with perhaps more truth than he is conscious of, ‘the Sirens are a kind of souls living the life of the spirit.’ His interpretation is not merely fanciful; it is a blend of primitive tradition with mystical philosophy. The Sirens are further helped to their high station on the spheres by the Orphic belief that purified souls went to the stars, nay even _became_ stars. In the _Peace_ of Aristophanes[528] the servant asks Trygaeus, ‘It is true then, what they say, that in the air A man becomes a star, when he comes to die?’ To the poet the soul is a bird in its longing to be free: ‘Could I take me to some cavern for mine hiding, On the hill-tops, where the sun scarce hath trod, Or a cloud make the place of mine abiding, As a bird among the bird-droves of God[529].’ And that upward flight to heavenly places is as the flying of a Siren: ‘With golden wings begirt my body flies, Sirens have lent me their swift winged feet, Upborne to uttermost ether I shall meet And mix with heavenly Zeus beyond the skies[530].’