When a new power rises, it often appears to be a providential turnover, Sir John Glubb notes:
Whatever causes may be given for the overthrow of great civilisations by barbarians, we can sense certain resulting benefits. Every race on earth has distinctive characteristics. Some have been distinguished in philosophy, some in administration, some in romance, poetry or religion, some in their legal system. During the pre-eminence of each culture, its distinctive characteristics are carried by it far and wide across the world.
If the same nation were to retain its domination indefinitely, its peculiar qualities would permanently characterise the whole human race. Under the system of empires each lasting for 250 years, the sovereign race has time to spread its particular virtues far and wide. Then, however, another people, with entirely different peculiarities, takes its place, and its virtues and accomplishments are likewise disseminated. By this system, each of the innumerable races of the world enjoys a period of greatness, during which its peculiar qualities are placed at the service of mankind.
To those who believe in the existence of God, as the Ruler and Director of human affairs, such a system may appear as a manifestation of divine wisdom, tending towards the slow and ultimate perfection of humanity.