To arrive at the concept of the Madonna, a far-reaching process of synthesis and reinterpretation must have been carried out before the Bible could be brought into harmony with the demands made by a cult of a mother goddess. Just as the views brought into the church by celibate ideals spread among heathen people, so the church must have been in its turn influenced by the heathen way of looking at things.[17] One of the great difficulties was the reconciliation of the biological process of procreation with divinity. But there had for ages been among primitive peoples the belief that impregnation was caused by spirit possession or by sorcery. This explanation had survived in a but slightly altered form in the ancient mythologies, all of which contained traditions of heroes and demi-gods who were born supernaturally of a divine father and a human mother. In the myths of Buddha, Zoroaster, Pythagoras and Plato, it was intimated that the father had been a god or spirit, and that the mother had been, and moreover remained after the birth, an earthly virgin. These old and precious notions of the supernatural origin of great men were not willingly renounced by those who accepted the new religion; nor was it necessary to make such a sacrifice, because men thought that they could recognize in the Jewish traditions something corresponding to the heathen legends.[18] The proper conditions for the development of a mother cult within Christianity existed within the church by the end of the second century. At the Council of Nicæa (325 A.D.) it was settled that the Son was of the same nature as the Father. The question of the nature of Mary then came to the fore. The eastern fathers, Athanasius, Ephraim Syrus, Eusebius and Chrysostom, made frequent use in their writings of the term Theotokos, Mother of God. When Nestorius attacked those who worshipped the infant Christ as a god and Mary as the mother of God rather than as the mother of Christ, a duel began between Cyril of Alexandria and Nestorius "which in fierceness and importance can only be compared with that between Arius and Athanasius."[19] In 431 A.D. the Universal Church Council at Ephesus assented to the doctrine that Mary was the Mother of God. Thus Ephesus, home of the great Diana, from primitive times the centre of the worship of a goddess who united in herself the virtues of virginity and motherhood, could boast of being the birthplace of the Madonna cult. And thus Mary, our Lady of Sorrows, pure and undefiled, "the church's paradox," became the ideal of man. She was "a woman, virgin and mother, sufficiently high to be worshipped, yet sufficiently near to be reached by affection. ... If we judge myths as artistic creations we must recognize that no god or goddess has given its worshippers such an ideal as the Mary of Christian art and poetry."[19: p.183] [20: v. ii., pp.220f.]