=40.= The prominence given to fire in the system of Heraclitus has very naturally suggested that his doctrine is borrowed from that of Zarathustra[45]. The historical circumstances are not unfavourable to this suggestion. Ionia was conquered in turn by Cyrus and Darius, and definitely annexed by Persia about 496 B.C., that is, at the very time at which Heraclitus taught. Moreover the Persian invasion was akin to a religious crusade, and had for a principal aim the stamping out of the idle and superstitious habit of worshipping images, by which (according to the Persians) the true God was dishonoured. The elevated character of the Persian religion could hardly fail to attract learned Greeks, already dissatisfied with the crude mythology of their own people. Further, the resemblance between the teaching of Zarathustra and that of Heraclitus is not restricted to the language used of the divine fire; the doctrines of an all-creating, all-pervading Wisdom, the λόγος or Word, and of the distinction between the immortal soul and the corruptible body, are common to both. But the differences between the two systems are almost equally striking. Heraclitus is a monist; according to him all existences are ultimately one. Zarathustra taught a principle of Evil, everywhere opposed to the Good Spirit, and almost equally powerful; his system is dualist[45a]. Zarathustra is not free from nationalism, Heraclitus is cosmopolitan. In the Ephesian system we find no trace of the belief in Judgment after death, in Heaven, or in Hell. We may in fact well believe that Heraclitus was acquainted with Zoroastrianism and influenced by it, but we have not the means to determine what the extent of that influence was. It is related of him that he received (but declined) an invitation to the court of Darius; and that his dead body was given up to be torn to pieces by dogs in the Persian fashion[45b]. [Sidenote: The tragedians.]