Secrecy was long imposed on the Motazilites by the orthodoxy of the Khalifs, [1064] who as a rule atoned for many crimes and abundant breaches of the law of the Koran by a devout profession of faith. Freethinking, however, had its periods of political prosperity. Even under the Ommayade dynasty, the Khalif Al Walid Ibn Yazid (the eleventh of the race) was reputed to be of no religion, but seems to have been rather a ruffian than a rationalist. [1065] Under the Abassides culture made much more progress. The Khalif Al Mansour, though he played a very orthodox part, [1066] favoured the Motazilites (754-775), being generally a patron of the sciences; and under him were made the first translations from the Greek. [1067] Despite his orthodoxy he encouraged science; and it was as insurgents and not as unbelievers that he destroyed the sect of Rewandites (a branch of the anti-Moslem Ismailites), who are said to have believed in metempsychosis. [1068] Partly on political but partly also on religious grounds his successor Al Mahdi made war on the Ismailites, whom he regarded as atheists, and who appear to have been connected with the Motazilite "Brethren of Purity," [1069] destroying their books and causing others to be written against them. [1070] They were anti-Koranites; hardly atheists; but a kind of informal rationalism approaching to atheism, and involving unbelief in the Koran and the Prophet, seems to have spread considerably, despite the slaughter of many unbelievers by Al Mahdi. Its source seems to have been Persian aversion to the alien creed. [1071] The great philosophic influence, again, was that of Aristotle; and though his abstract God-idea was nominally adhered to, the scientific movement promoted above all things the conception of a reign of law. [1072] Al Hadi, the successor of Al Mahdi, persecuted much and killed many heretics; and Haroun Al Raschid (Aaron the Orthodox) menaced with death those who held the moderately rational tenet that "the Koran was created," [1073] as against the orthodox dogma (on all fours with the Brahmanic doctrine concerning the Veda) that it was eternal in the heavens and uncreated. One of the rationalists, Al Mozdar, accused the orthodox party of infidelity, as asserting two eternal things; and there was current among the Motazilites of his day the saying that, "had God left men to their natural liberty, the Arabians could have composed something not only equal but superior to the Koran in eloquence, method, and purity of language." [1074]