Many other great philosophers of classical antiquity, especially Democritus, Heraclitus, and Empedocles, had, in the same or an analogous sense, a profound conception of this unity of nature and God, of body and spirit, which has obtained its highest expression in the law of substance of our modern monism. The famous Roman poet and philosopher, Lucretius Carus, has presented it in a highly poetic form in his poem "De Rerum Natura." However, this true pantheistic monism was soon entirely displaced by the mystic dualism of Plato, and especially by the powerful influence which the idealistic philosophy obtained by its blending with Christian dogmas. When the papacy attained to its spiritual despotism over the world, pantheism was hopelessly crushed; Giordano Bruno, its most gifted defender, was burned alive by the "Vicar of Christ" in the Campo dei Fiori at Rome on February 17, 1600. It was not until the middle of the seventeenth century that pantheism was exhibited in its purest form by the great Baruch Spinoza; he gave for the totality of things a definition of substance in which God and the world are inseparably united. The clearness, confidence, and consistency of Spinoza's monistic system are the more remarkable when we remember that this gifted thinker of two hundred and fifty years ago was without the support of all those sound empirical bases which have been obtained in the second half of the nineteenth century. We have already spoken, in the first chapter, of Spinoza's relation to the materialism of the eighteenth and the monism of the nineteenth century. The propagation of his views, especially in Germany, is due, above all, to the immortal works of our greatest poet and thinker, Wolfgang Goethe. His splendid _God and the World_, _Prometheus_, _Faust_, etc., embody the great thoughts of pantheism in the most perfect poetic creations. Atheism affirms that there are no gods or goddesses, assuming that god means a personal, extramundane entity. This "godless world-system" substantially agrees with the monism or pantheism of the modern scientist; it is only another expression for it, emphasizing its negative aspect, the non-existence of any supernatural deity. In this sense Schopenhauer justly remarks: "Pantheism is only a polite form of atheism. The truth of pantheism lies in its destruction of the dualist antithesis of God and the world, in its recognition that the world exists in virtue of its own inherent forces. The maxim of the pantheist, 'God and the world are one,' is merely a polite way of giving the Lord God his _congé_."