We may rightly refer to this period as a renascence, for it meant quickening into new and other life the embers of the later Hellenistic culture, and especially of the Aristotelian philosophy and medical and natural science, which had never quite died away in Western Asia, but had been checked by its passage into Syriac-speaking and Persian-speaking communities, amongst whom the language in which the original authorities were written was only imperfectly known. Thus Hellenism suffered a phase of provincialism, which came to an end when Arabic appeared as a more or less cosmopolitan language, and thought began to be exchanged by different races and social groups. Under the early ʿAbbasids, and especially under the Khalif al-Maʾmun (A.H. 198-218), there was a vast amount of translation from Greek into Arabic until the greater part of Aristotle, of the neo-Platonic commentators on Aristotle, of Galen, some parts of Plato, and other material, were freely accessible to the Muslim world: whilst at the same time translations were made from Indian writers on mathematics, medicine, and astronomy, some directly from the Sanskrit, and others from old Persian versions. As a result the philosophical speculations of the Greeks began to act as a solvent upon Islamic theology, and from this doctrinal discussions and controversies arose which, on the one side, produced a series of rationalistic heresies, and on the other side laid the foundations of an orthodox Muslim scholasticism. Long before this Hellenistic influences had permeated Persia and Mesopotamia, and these now revived and resulted in a philosophical presentation of religion which, under the veil of allegorical explanations of the Qurʾan, was really undermining orthodox doctrine, and heading towards either pantheism or simple agnosticism. With these tendencies the pro-Persian party was particularly associated. The Khalifs who, in spite of Arab birth, were most devoted to Persian ideas, largely because the Persians were subtle courtiers and were the champions of absolutism, were amongst those most ardent in promoting the study of Greek philosophy; and the Imams, such as Jaʿfar and his brother Zayd, were even more devotedly attached to this type of philosophical speculation which was acting as a powerful solvent on the traditional beliefs of orthodox Islam.