For Herodotus, meanwhile, language and culture can change under stress of circumstances in just the same way as physique; and therefrom follows the possibility of the transmission of culture. Whether any particular custom was to be regarded as innate in the φύσις of those who practised it, or as their response to the stresses of their present environment, or as the result, whether conformable to the environment or not, of intercourse with another variety of Man, was a question to be settled on the merits of each case. It was, in fact, partly the laxness of interest in such matters which resulted from the prevalent theory, and only partly the admitted incompleteness of the observations, that kept ethnographical speculation in so backward a state as we find it in Herodotus’ time. Until the belief in stronger specific characters could be supplemented by some doctrine of cultural momentum, the conception of progress in civilization was hardly attainable at all. This is where the treatment of Hellenic civilization by Herodotus stands in so marked a contrast with his treatment of the civilizations of Egypt and Outland. Egyptian civilization, like Egypt itself, is the gift of the Nile; the φύσις of an Indian attains its τέλος when he has ridden his camels and rescued his gold; the men are black, or tall, or longlived as the effect of natural causes; and as long as these causes persist, so long will there be Indians or Aethiopians with those qualities. Only in Greece is there mastery of man over nature, and that not because nature is less strong, but because Greek man is strong enough to dominate it.