“You must conceive it” (the whirl) “to be of such a kind as this:  as if in some great hollow whirl, carved throughout, there was such another, but lesser, within it, adapted to it, like casks fitted one within another; and in the same manner a third, and a fourth, and four others, for that the whirls were eight in all, as circles one within another…and that in each of its circles there was seated a siren on the upper side, carried round, and uttering one voice variegated by diverse modulations; but that the whole of them, being eight, composed one harmony.”  (Plat., Rep. x. 14, Davies’ Trans.)  Plato describes the Fates “singing to the harmony of the Sirens.”  Id.  On the Pythagorean Music of the Spheres, cf. also Cic., De Divin. i. 3, and Macrobius In Somn:  Scip. cf. Shaksp., M. of Ven. v. 1: “There’s not the smallest orb which thou behold’st But in his motion like an angel sings, Still quiring to the young-eyed cherubim.” And Milton, Arcades: “Then listen I To the celestial Sirens’ harmony, That sit upon the nine infolded spheres, And sing to those that hold the vital sheres, And turn the adamantine spindle round On which the fate of gods and men is wound.