In the first place, the earliest Chaldæan legends already exhibit the rudiments of that sevenfold division of the Heavens which was generally adopted by Jewish and Christian writers alike, and ultimately received the sanction of the scholastic divines. The science, if it can be so called, of numbers is one of the most fertile of the many fields which a perverted ingenuity has devoted to the assiduous cultivation of tares, and hardly any number has been accredited with a greater variety of significance than the number seven, by reason, doubtless, of the primitive astronomical theory of the seven planets. Dante, indeed, raised the number of heavens to ten, in accordance with the astronomical system that had come to be adopted in his day, on the authority of the ancient cosmologists, introduced to the mediæval students through Arab channels; to the original seven planetary heavens he added three others--the Heaven of fixed stars, the crystalline Heaven, and the Empyrean. We may remark, in passing, that the Samoan cosmology agrees with Dante in this tenfold division of the Heavens. In the Chaldæan mythology this conception of a sevenfold division occurs in germ only, but the Seven Magnificent Deities--the precursors of the seven Amesha Spentas, and the seven Archangels of the Hebrew and Christian divines--who preside over the several powers of nature, lend themselves easily to the attribution of separate territories in the celestial domain. The beginning of this phase is apparent in the seven portals, each guarded by a porter, through which Ishtâr had to pass on her way to the abode of the gods and of the dead, even as the spirit of Adamnán had to pass through seven ‘Heavens,’ so-called, the door of each being kept by an angelic warder; while the symbolism embodied in the gradual spoliation of Ishtâr of her earthly raiment is analogous to the gradual purgation of the soul from its earthly stains in the Christian legend.