The origin of a people can be investigated and stated only in terms of geography. The problem of origin can be solved only by tracing a people from its present habitat, through the country over which it has migrated, back to its original seat. Here are three geographical entities which can be laid down upon a map, though seldom with sharply defined boundaries. They represent three successive geographic locations, all embodying geographic conditions potent to influence the people and their movement. Hence the geographical element emerges in every investigation as to origins; whether in ethnology, history, philology, mythology or religion. The transit land, the course between start and finish, is of supreme importance. Especially is this true for religion, which is transformed by travel. Christianity did not conquer the world in the form in which it issued from the cramped and isolated environment of Palestine, but only after it had been remodelled in Asia Minor, Egypt, Greece and Rome, and cosmopolized in the wide contact of the Mediterranean basin. The Roman speech and civilization, which spread through the Romance speaking peoples of Europe, were variously diluted and alloyed before being transplanted by French, Spaniard and Portuguese to American shores, there to be further transformed. [Sidenote: Large centers of dispersion.] In view of the countless springs and tributaries that combine to swell the current of every historical movement, anthropo-geography looks for the origin of a people not in a narrowly defined area, but in a broad, ill-defined center of dispersion, from which many streams simultaneously and successively flow out as from a low-rimmed basin, and which has been filled from many remoter sources. Autochthones, aborigines are therefore merely scientific tropes, indicating the limit beyond which the movement of people cannot be traced in the gray light of an uncertain dawn. The vaguer and more complex these movements on account of their historical remoteness, the wider their probable range. The question as to the geographical origin of the Aryan linguistic family of peoples brings us to speculative sources, more or less scientifically based, reaching from Scandinavia and Lithuania to the Hindu Kush Mountains and northern Africa.[236] The sum total of all these conjectural cradles, amounting to a large geographical area, would more nearly approximate the truth as to Aryan origins. For the study of the historical movement makes it clear that a large, highly differentiated ethnic or linguistic family presupposes a big center end a long period of dispersion, protracted wanderings, and a diversified area both for their migrations and successive settlements. [Sidenote: Small centers.]