The fact that the celestial bodies were observed to revolve around a fixed point rendered it a necessity that this assumed support of the heaven should be of the nature of a central axis, upholding the sky-roof as the pole upholds a tent. To the inhabitants of mountainous countries, who saw the clouds resting upon the peaks, the idea of a heaven-supporting mountain no doubt presented itself as the most reasonable solution. Thus Aristotle, to quote Lord Bacon, “elegantly expoundeth the ancient fable of Atlas (that stood fixed and bare up the heaven from falling) to be meant of the poles or axle-tree of heaven.” To plain-dwellers, however, the tree was the loftiest object within their experience, and it may be conjectured that the idea of a central world-supporting tree was a product of the lowlands. In some cases the two conceptions were combined and the world-tree was placed on the summit of a world-mountain. It is interesting, however, to note that the earliest known version of a world-tree, pure and simple, comes to us from the fertile alluvial plain on the borders of the Persian Gulf. The account, contained in an old bilingual hymn, and probably of Accadian origin, represents the tree as growing in the garden of Edin or Eden, placed by Babylonian tradition in the immediate vicinity of Eridu, a city which flourished at the mouth of the Euphrates between 3000 and 4000 B.C. In Eridu a stalk grew overshadowing; in a holy place did it become green; Its roots were of white crystal, which stretched towards the deep. (Before) Ea was its course in Eridu, teeming with fertility; Its seat was the (central place of the earth); Its foliage (?) was the couch of Zikum the (primaeval) mother. Into the heart of its holy house, which spread its shade like a forest, hath no man entered. (There is the home) of the mighty mother who passes across the sky. In the midst of it was Tammuz. There is the shrine of the two (gods).[260] Of this glorified tree or stem it is to be observed that it grew at the centre of the earth; that its roots pierced down into the abysmal watery deep, where the amphibious Ea, the god of wisdom, had his seat, and whence he nourished the earth with springs and streams; that its foliage supported Zikum, the primordial heavens, and overshadowed the earth, which was apparently regarded as a plane placed midway between the firmament above and the deep below. The stem itself was the home of Davkina, consort of Ea, the great mother, “the lady of the Earth,” and of her son Tammuz, a temple too sacred for mortals to enter.