Two other causes which have been potent in bringing about displacements and mixtures of population are the desire for conquest and plunder and the sentiment of religion. But these belong less to the sphere of Nature than to that of human passion and emotion, so that they scarcely fall within this part of our inquiry, the aim of which has been to show how Nature has determined history by inducing a shifting of races from place to place. From this shifting there has come the contact of diverse elements, with changes in each race due to the influence of the other, or perhaps the absorption of one in the other, or the development of something new out of both. In considering these race movements we have been led from the remote periods in which they began, and of which we know scarcely anything except from archæological and linguistic data, to periods within the range of authentic history. So we may go on to see how Nature has determined the spots in which the industry of the more advanced races should build up the earliest civilisations, and the lines along which commerce, a principal agent in the extension of civilisation, should proceed to link one race with another. [Illustration: THE MERCHANT MARINERS OF THE ANCIENT WORLD The earliest agents in the diffusion of trades and the arts were the Phœnicians, who from their great cities of Tyre, Sidon, and Carthage conducted a sea-borne traffic with lands as remote as England, and whose adventurous sailors, despite the smallness of their vessels, are believed even to have succeeded in rounding the Cape of Good Hope. ] [Sidenote: Isolation of Eastern Peoples]