At first, it was only at Medina that some pious people occupied themselves with registering, putting in order, and systematizing the spiritual property of Islâm; afterwards similar circles were formed in other centres, such as Mecca, Kufa, Basra, Misr (Cairo), and elsewhere. At the outset the collection of divine sayings, the Qorân, was the only guide, the only source of decisive decrees, the only touchstone of what was true or false, allowed or forbidden. Reluctantly, but decidedly at last, it was conceded that the foundations laid by Mohammed for the life of his community were by no means all to be found in the Holy Book; rather, that Mohammed's revelations without his explanation and practice would have remained an enigma. It was understood now that the rules and laws of Islâm were founded on God's word and on the Sunnah, _i.e._, the "way" pointed out by the Prophet's word and example. Thus it had been from the moment that Allah had caused His light to shine over Arabia, and thus it must remain, if human error was not to corrupt Islâm. At the moment when this conservative instinct began to assert itself among the spiritual leaders, so much foreign matter had already been incorporated into Islâm, that the theory of the sufficiency of Qorân and Sunnah could not have been maintained without the labelling operation which we have alluded to. So it was assumed that as surely as Mohammed must have surpassed his predecessors in perfection and in wonders, so surely must all the principles and precepts necessary for his community have been formulated by him. Thus, by a gigantic web of fiction, he became after his death the organ of opinions, ideas, and interests, whose lawfulness was recognized by every influential section of the Faithful. All that could not be identified as part of the Prophet's Sunnah, received no recognition; on the other hand, all that was accepted had, somehow, to be incorporated into the Sunnah. It became a fundamental dogma of Islâm, that the Sunnah was the indispensable completion of the Qorân, and that both together formed the source of Mohammedan law and doctrine; so much so that every party assumed the name of "People of the Sunnah" to express its pretension to orthodoxy. The _contents_ of the Sunnah, however, was the subject of a great deal of controversy; so that it came to be considered necessary to make the Prophet pronounce his authoritative judgment on this difference of opinion. He was said to have called it a proof of God's special mercy, that within reasonable limits difference of opinion was allowed in his community. Of that privilege Mohammedans have always amply availed themselves.