So a habitat leaves upon man no ephemeral impress; it affects him in one way at a low stage of his development, and differently at a later or higher stage, because the man himself and his relation to his environment have been modified in the earlier period; but traces of that earlier adaptation survive in his maturer life.

Hence man's relation to his environment must be looked at through the perspective of historical development.

It would be impossible to explain the history and national character of the contemporary English solely by their twentieth century response to their environment, because with insular conservatism they carry and cherish vestiges of times when their islands represented different geographic relations from those of to-day.

Witness the wool-sack of the lord chancellor.

We cannot understand the location of modern Athens, Rome or Berlin from the present day relations of urban populations to their environment, because the original choice of these sites was dictated by far different considerations from those ruling to-day.