This conception of the relation of geography to history is, as has been said, the leading idea of the present work, and has furnished the main lines which it follows. It deals with history in the light of physical environment. Its ground plan, so to speak, is primarily geographical, and secondarily chronological. But there is one difficulty in the way of such a scheme, and of the use of such a ground plan, which cannot be passed over. That difficulty is suggested by the fact already noted--that hardly any considerable race, and possibly no great nation, now inhabits the particular part of the earth’s surface on which it was dwelling when a history begins. Nearly every people has either migrated bodily from one region to another, or has received such large infusions of immigrants from other regions as to have become practically a new people. Hence it is rare to find any nation now living under the physical conditions which originally moulded its character, or the character of some at least of its component elements. And hence it follows that when we study the qualities, aptitudes, and institutions of a nation in connection with the land it inhabits, we must always have regard not merely to the features of that land, but also to those of the land which was its earlier dwelling-place. Obviously, this brings a disturbing element into the study of the relations between land and people, and makes the whole problem a far more complicated one than it appeared at first sight. [Sidenote: Nature’s Race Factory] Where a people has migrated from a country whose physical conditions were similar to those under which its later life is spent, or where it had reached only a comparatively low stage of economic and political development before the migration, the difficulties arising from this source are not serious. The fact that the English came into Britain from the lands round the mouth of the Elbe is not very material to an inquiry into their relations to their new home, because climate and soil were similar, and the emigrants were a rude, warlike race. But when we come to the second migration of the English, from Britain to North America, the case is altogether different. Groups of men from a people which had already become highly civilised, had formed a well-marked national character, and had created a body of peculiar institutions, planted themselves in a country whose climate and physical features are widely diverse from those of Britain.