Beyond such interpretative principles for special phases of civilization, there are still broader generalizations of cultural phenomena. One has been repeatedly alluded to under the caption of cultural inertia, or survival--the irrational persistence of a feature when the context in which it had a place has vanished. But culture is not merely a passive phenomenon but a dynamic one as well. This is strikingly illustrated in the assimilation of an alien cultural stimulus. As I have already pointed out, it is not sufficient to bring two cultures into contact in order to have a perfect cultural interpenetration. The element of selection enters in a significant way. Not everything that is offered by a foreign culture is borrowed. The Japanese have accepted our technology but not our religion and etiquette. Moreover, what is accepted may undergo a very considerable change. While the whole range of phenomena is extremely wide and cannot be dismissed with a few words, it appears fairly clear that generally the preëxisting culture at once seizes upon a foreign element and models it in accordance with the _native_ pattern. Thus, the Crow Indians, who had had a pair of rival organizations, borrowed a society from the Hidatsa where such rivalry did not exist. Straightway, the Crow imposed on the new society their own conception, and it became the competitor of another of their organizations. Similarly the Pawnee have a highly developed star cult. Their folklore is in many regards similar to that of other Plains tribes, from which some tales have undoubtedly been borrowed. Yet in the borrowing these stories became changed and the same episodes which elsewhere relate to human heroes now receive an astral setting. The preëxisting cultural pattern synthetizes the new element with its own preconceptions.