There has been an obvious need for a comprehensive study on the value of colonies. Mr. Clark has to a large extent stopped that gap. He proves that, by and large, the colony-holding nations have not got their money's worth from their overseas possessions, either as markets for manufactured goods, as sources of raw materials, or as outlets for surplus population. Trade, he demonstrates, seldom follows the flag. He tends to ignore, however, that certain colonies have paid richly, and that though the colonizing nations may on the whole have gained few calculable economic advantages from their empires, certain individuals or social groups in those nations have profited. He also fails to give proper weight to the intangible but very important political factor in modern imperialism. He concludes by suggesting that a form of the mandate system be extended to the administration of all colonies.