If the rivers helped man, man also helped the rivers by inventing systems of irrigation.

Next, from Minoan days right on to the end of the Middle Ages, the Mediterranean basin was the focus of all the higher life in the world, if we put out of sight the civilizations of India and China, together with the lesser cultures of Peru and Mexico.

I will consider this second phase especially, because it is particularly instructive from the geographical standpoint.

Finally, since the time of the discovery of America, the sea-trade, first called into existence as a civilizing agent by Mediterranean conditions, has shifted its base to the Atlantic coast, and especially to that land of natural harbours, the British Isles.

We must give up thinking in terms of an Eastern and Western Hemisphere.