Manichæism is a religion founded by the Persian Mani in the latter half of the third century. It purported to be the true synthesis of all the religious systems then known, and actually consisted of Zoroastrian Dualism, Babylonian folklore, Buddhist ethics, and some small and superficial, additions of Christian elements. As the theory of two eternal principles, good and evil, is predominant in this fusion of ideas and gives color to the whole, Manichæism is classified as a form of religious Dualism. It spread with extraordinary rapidity in both East and West and maintained a sporadic and intermittent existence in the West (Africa, Spain, France, North Italy, the Balkans) for a thousand years, but it flourished mainly in the land of its birth, (Mesopotamia, Babylonia, Turkestan) and even further East in Northern India, Western China, and Tibet, where, c. A.D. 1000, the bulk of the population professed its tenets and where it died out at an uncertain date.After Augustine became bishop the zeal which, from the time of his baptism, he had manifested in bringing his former co-religionists into the true Church, took on a more paternal form without losing its pristine ardour - "let those rage against us who know not at what a bitter cost truth is attained. . . . As for me, I should show you the same forbearance that my brethren had for me when I blind, was wandering in your doctrines" (Contra Epistolam Fundamenti 3). Among the most memorable events that occurred during this controversy was the great victory won in 404 over Felix, one of the "elect" of the Manichæans and the great doctor of the sect. He was propagating his errors in Hippo, and Augustine invited him to a public conference the issue of which would necessarily cause a great stir; Felix declared himself vanquished, embraced the Faith, and, together with Augustine, subscribed the acts of the conference. In his writings Augustine successively refuted Mani (397), the famous Faustus (400), Secundinus (405), and (about 415) the fatalistic Priscillianists whom Paulus Orosius had denounced to him. These writings contain the saint's clear, unquestionable views on the eternal problem of evil, views based on an optimism proclaiming, like the Platonists, that every work of God is good and that the only source of moral evil is the liberty of creatures (City of God XIX.13.2). Augustine takes up the defence of free will, even in man as he is, with such ardour that his works against the Manichæan are an inexhaustible storehouse of arguments in this still living controversy.