It is known also that the posterity of the first crusaders in Palestine formed a hybrid race, which, weakened by the influence of the luxurious habits of Eastern countries, became corrupt, and under the name of Pulani practised a feeble Christianity, unfit to cope with the vigorous fanaticism of the Mussulman. Many Europeans came back from those wars wavering in faith, and no one knows how many with faith entirely lost. It is not, therefore, too much to suppose that the Oriental errors which suddenly burst forth at this time in Western Europe followed in the wake of the returning pilgrims, and it is highly probable, if not absolutely certain, that, had there been no Crusades, Manicheism and the secret societies born of it would never have been known in Italy and France. Hence, one of the first and greatest champions of the Church in controversy with the Albigenses - Peter the Venerable, Abbot of Cluny - at the very beginning of the heresy, found no better means of opposing the new errors than attacking every thing coming from the East. Thus, he wrote his long treatises against the Talmud and the Koran, so much had the Crusades already contributed to introducing into Western Europe the seeds of Asiatic errors. All historians agree in giving an Eastern origin to the Paulicians, Bulgarians, Albigenses, and others of those times. Manicheism indeed had infested Europe long before. Some Roman emperors had published severe edicts against it. In the fifth century, the heresy still flourished in Italy and Africa, St. Augustine himself being an adept for several years, and by his writings he has made us acquainted with its strongest supporters in his day. He was followed, in his attacks on it, by a great number of Fathers, both Greek and Latin. But after the barbarian invasions we hear no more of the Manichees for upward of five hundred years. The West had entirely forgotten them. Arianism and Manicheism had apparently perished together. The tenth century is called a period of darkness and ignorance; it at least possessed the advantage of being free from heresy; the dogmas of the Church were unhesitatingly and universally accepted. Western Europe, though cut up by the new-born feudalism into a thousand fragments, was at least one in faith, until that great and powerful union having, in an outburst of enthusiasm, produced the Crusades, we suddenly find Eastern theories and immoralities invading the countries most faithful to the Church.