which indeed constitutes the very foundation of Islam, namely, the conception of a severe and uncompromising monotheism.[10] The fact is that both Judaism and Christianity were used and used freely by the prophet in building up his religion. Nor is this a new theory. The prophet never put himself forward as introducing something new but he invariably claimed for himself the honour of reviving the old and the true beliefs which had fallen into neglect and oblivion. But besides the Jewish and Christian sources, not a small portion of Islamic ritual and ceremonials were mere reproductions of Pre-Islamic practices. The entire ceremonies relating to the pilgrimage (Hajj) and the sacred service, at the temple of Mecca, have survived in Islam with little or no variation from the days of Arab Heathenism;[11] the only change that Mohamed effected in them was to allow the pilgrims to put on a particular pilgrim dress consisting of two pieces of cloth of which one covers the hip and the other breast and shoulders; while the head has to be kept uncovered, as in ancient days, when they used to make up their hair into a sort of wig by means of some glutinous substance. And so indeed it has remained, to this day, the prescribed pilgrim costume. After visiting the Kabah they used, in heathen days, to visit the two rocky hills of Safa and Merwah on which were placed two bronze idols. Mohamed went so far in his toleration of the heathen pilgrimage customs that he suffered the visit to Safa and Marwah to continue as before, but had the two idols removed. Of the history of the origin of the forms of the prayer, prostration, ablution, and fasts our knowledge is vague, uncertain and shadowy. Islam has, says Von Kremer, largely drawn upon Judaism, Christianity, the religion of Zoroaster and possibly even from Manichenism. From Parsiism it has taken both directly and indirectly. A number of obviously Parsi ideas have penetrated into Islam through the channel of Jewish books; notably the Talmud. The doctrine of the resurrection, most of the legends relating to heaven and hell, and the entire system of demonology have found their way into the Qur´an through Judaism. So indeed did the description of the trial and the tortures of the dead in the grave by two angels _Munkar_ and _Nakir_. The idea of the bridge _sirat_ as thin as a hair, which leads to paradise across the abyss of hell is certainly derived from the Parsis; having passed over into the Qur´an through the Midrash. But Islam has not hesitated to borrow directly from Parsiism. It is a significant fact that the word _din_, which so repeatedly occurs in the Qur´an, has been borrowed from the Parsi books. In the Huzveresh it appears in exactly the same form (old Backtrian dæna).[12]