Civilizations in decline are consistently characterized by a tendency towards standardization and uniformity. - Arnold J. Toynbee

The value of the goal lies in the goal itself; and therefore the goal cannot be attained unless it is pursued for its own sake.

"These societies have no common characteristic beyond the fact that all of them are "intelligible fields of study ", and this characteristic is so vague and general that it can be turned to no practical account."

We may express the historical function of the 'Abbasid Caliphate by describing it as a reintegration and resumption of the Achaemenian Empire - a reintegration of a political structure which had been broken up by the impact of an external force and the resumption of a phase of social life which had been interrupted by an alien intrusion.