vagaries in transmission of the word of god

Whether the Koran was written down in full during Mohammed's lifetime is a question on which there are conflicting traditions. The generally received account describes its first compilation a few years after his death from scraps of parchment and leather, tablets of stone, ribs of palm trees, camels' shoulder-blades and ribs, pieces of board and the breasts of men. To this, probably, is to be ascribed much of the unevenness and rough jointing which characterize the present composition of the longer suras. It is certain that, alongside these written materials, several of the Companions of the Prophet preserved by heart and transmitted versions with numerous small variants, and that the third Caliph, Othman, had an authoritative text prepared at Medina, copies of which were sent to the chief cities.

These copies, however, were written in the very defective early Arabian script, which needed to be supplemented by the trained memories of the thousands of reciters. To meet this difficulty, improvements and refinements of orthography were gradually introduced into the old manuscripts. By the end of the first [Muslim] century the text as we now have it had been stabilized in all but a few details ...

Yet so many minor variations in reading and punctuation still survived that ultimately the problem had to be met by a characteristic Muslim compromise ... first ten and then seven famous reciters were recognized as authoritative teachers and all their readings were accepted as orthodox. Although the learned claimed the right to accept the readings of other teachers, for all public purposes readings according to the text of one or other of the Seven only were adopted. In course of time several of these also dropped out of use, but it is only in the present century [i.e. the 20th] (as a result of the dissemination of printed and lithographed copies of the Koran from Constantinople and Cairo) that a single reading has acquired almost universal currency in the Muslim world.

from: Mohammedanism, An Historical Survey, by H.A.R. Gibb, OUP, 1969