The Greek view of nature was essentially pantheistic. The Ionian speculators appear to have presumed without expressly insisting upon its self-regulating power. Aristotle alone emphatically rejected the doctrine of cosmic vitality or sub-conscious tendencies. But Plato accepted and magnified the Oriental tradition; the conception of a 'World-Soul' owed to him its vague splendour and perennial fascination. The function of the Platonic vice-creator (for such the World-Soul must be accounted) was that of moulding brute matter into conformity with the archetypal ideas of the Divine mind; this was not, however, accomplished once for all, but by a progressive spiritualizing of what in its nature was dead and inanimate. The spiritual agent, becoming incorporated with the universal frame, lent to it a semblance of life, an obscure sensitiveness, and even some kind of latent intelligence; and so the _anima mundi_ was shaped into existence, and continued century by century to be the subject and source of imaginings beyond measure wild and fantastic. One great thought--that of the unity of nature--lay behind them, but its significance was lost amid the phantasmagoria of Neo-Platonist exaltations. Hence the Bacchic fervours of Giordano Bruno took their inspiration; here was the groundwork of Spinoza's pantheism. Shelley's Demiorgon, felt as 'a living spirit,' seen as 'a mighty darkness,' descended lineally from that strange essence--formless, inarticulate, devoid of individual self-consciousness--which animated the submerged philosophy of Neo-Pagan times with the barren ardours of mysticism. The doctrine, in its original and more sober version, obtained memorable expression in Virgil's melodious hexameters: 'Principio cœlum, ac terras, camposque liquentes, Lucentemque globum lunæ, Titaniaque astra, Spiritus intus alit, totamque infusa per artus Mens agitat molem, et magno se corpore miscet.' In Conington's rhymed version they run as follows: 'Know first, the heaven, the earth, the main, The moon's pale orb, the starry train, Are nourished by a soul, A bright intelligence, whose flame Glows in each member of the frame, And stirs the mighty whole.'