community, as we descend, is modified by its predecessors. The converse
is no doubt true also, but commonly in less degree.

In this way with the geographer we may rapidly review and extend our
knowledge of the grouping of cities. Such a survey of a series of our
own river-basins, say from Dee to Thames, and of a few leading
Continental ones, say the Rhine and Meuse, the Seine and Loire, the
Rhone, the Po, the Danube--and, if possible, in America also, at least
the Hudson and Mississippi--will be found the soundest of introductions
to the study of cities. The comparison of corresponding types at once
yields the conviction of broad general unity of development, structure,
and function. Thus, with Metschnikoff we recognise the succession of
potamic, thalassic, and oceanic civilisations; with Reclus we see the
regular distribution of minor and major towns to have been largely
influenced not only by geographical position but by convenient journey
distances. Again, we note how the exigencies of defence and of
government, the developments of religion, despite all historic
diversities, have been fundamentally the same. It is not, of course, to
be forgotten how government, commerce, communications, have
concentrated, altered or at least disguised the fundamental geographical
simplicity of this descending hierarchy from mountain-hamlet to
ocean-metropolis; but it is useful for the student constantly to recover
the elemental and naturalist-like point of view even in the greatest
cities. At times we all see London as still fundamentally an
agglomeration of villages, with their surviving patches of common,
around a mediaeval seaport; or we discern even in the utmost
magnificence of Paris, say its Place de l'Etoile, with its spread of
boulevards, but the hunter's tryst by the fallen tree, with its
radiating forest-rides, each literally arrow-straight. So the narrow
rectangular network of an American city is explicable only by the