It would be a mistake to view the intellectual and political movement of socialism as a clearly identifiable and neatly circumscribed historical structure. Out of the many strands which have gone into the making of “socialism” it is possible, by simplifying the complexity of the process, to select at least four broad sources of socialist inspiration and thus four different versions of the socialist goal. These different concepts of socialism are not to be identified with specific historical figures or groups or movements, but represent rather the basic social and psychological elements which combined in varying degree to form the socialist movements known to us. The crisis of modern socialism—as exhibited in the books under consideration—is due to the fact that each of these concepts, for different reasons, has reached a dead-end from which advance toward any one goal means retreat from others also previously embraced.