But some things are clear now. In some countries the survivors of the fighting have been promised "a land fit for heroes," and are busily searching for it. In others the old economic structure of society has collapsed already and the new structure, which will eventually replace it, is likely to differ widely from the old. In no country, it may safely be said. has the war failed to quicken men's criticism of the social order, and to strengthen their intolerance of all sharp economic contrasts, which appear to them to lack justification. Rather does it seem that throughout the world " there is a great tide flowing in the hearts of men," which will wash against the foundations of inequality, wherever they may be found, and may flow so strongly as to carry away many familiar landmarks.1 In such a situation there is both great promise of good and great danger of evil and, in order to realise the former and avoid the latter, each member of the community should make the contribution of thought and effort, of which he is most capable. Among the contributions which a student of economic science can best make is an attempt to solve some of those outstanding problems of economic cause and effect, which are relevant to the contrast of wealth and poverty, but for which complete solutions have not yet been found. This book is an attempt of this kind.