Interpolations in the Qur'an

Tradition tells us that the Qur'an was revealed in fragments over a period of some twenty years. It is also quite clear that the various portions of the text of the Qur'an were not revealed in the order in which they now appear. In many instances, in fact, the text of the Qur'an quite explicitly indicates that certain verses were revealed in response to questions asked of or by Muhammad. As a consequence, the Qur'an can be viewed as a reflexive text, meaning that it comments on itself.
The term interpolation is often used when referring to the practice of inserting foreign material into handwritten manuscripts. Sometimes this was done by scribes as a means of filling in gaps in damaged or incomplete texts, or sometimes it was done purposefully to alter or supplement a particular text, often to reflect the point of view of the person paying to have the manuscript copied.
I use the term interpolation in a more positive light to identify certain passages in the Qur'an that appear to have been placed at a particular position within a surah at a different time than the material that either precedes or surrounds them. I would suggest that the purpose of these interpolations was to clarify portions of the text, perhaps to prevent misinterpretation, or perhaps as a means of aiding the Prophet in acquiring a receptive audience for the message of the Qur'an. Whatever, the reason, in my view, the existence of interpolations in the text of Qur'an reinforces the idea that no message stands outside of the context in which it is transmitted.