A Hellenistic enthusiasm has led a series of eminent scholars to carry so far their resistance to the tradition of Oriental beginnings [406] as to take up the position that Greek thought is "autochthonous." [407] If it were, it could not conceivably have progressed as it did. Only the tenacious psychological prejudice as to race-characters and racial "genius" could thus long detain so many students at a point of view so much more nearly related to supernaturalism than to science. It is safe to say that if any people is ever seen to progress in thought, art, and life, with measurable rapidity, its progress is due to the reactions of foreign intercourse. The primary civilizations, or what pass for such, as those of Akkad and Egypt, are immeasurably slow in accumulating culture-material; the relatively rapid developments always involve the stimulus of old cultures upon a new and vigorous civilization, well-placed for social evolution for the time being. There is no point in early Greek evolution, so far as we have documentary trace of it, at which foreign impact or stimulus is not either patent or inferrible. [408] In the very dawn of history the Greeks are found to be a composite stock, [409] growing still more composite; and the very beginnings of its higher culture are traced to the non-Grecian people of Thrace, [410] who worshipped the Muses. As seen by Herodotos and Thucydides, "the original Hellenes were a particular conquering tribe of great prestige, which attracted the surrounding tribes to follow it, imitate it, and call themselves by its name. The Spartans were, to Herodotos, Hellenic; the Athenians, on the other hand, were not. They were Pelasgian, but by a certain time 'changed into Hellenes and learnt their language.' In historical times we cannot really find any tribe of pure Hellenes in existence." [411] The later supremacy of the Greek culture is thus to be explained in terms not of an abnormal "Greek genius," [412] but of the special evolution of intelligence in the Greek-speaking stock, firstly through constant crossing with others, and secondarily through its furtherance by the special social conditions of the more progressive Greek city-states, of which conditions the most important were their geographical dividedness and their own consequent competition and interaction. [413]