« Beyond doubt, Sogdian was the national language of the Majority of clerics and propagandidts of the Manichaean faith in Central Asia. Middle Persian (= Pārsīg), and to a lesser degree, Parthian (= Pahlavānīg), occupied the position held by Latin in the medieval church. The founder of Manichaeism had employed Syriac (his own language) as his medium, but conveniently he had written at least one book in Middle Persian, and it is likely that he himself had arranged for the translation of some or all of his numerous writings from Syriac into Middle Persian. Thus the Eastern Manichaeans found themselves entitled to dispense with the study of Mani’s original writings, and to continue themselves to reading the Middle Persian edition; it presented small difficulty to them to acquire a good knowledge of the Middle Persian language, owing to its affinity with Sogdian. … » W. B. Henning, Sogdica, 1940, 11.