Why the 19th-century balance of power evolved into two competing world-systems, revolutionary-socialist and legal-democratic; how the Cold War between them led to peaceful coexistence, or detente; what detente implies, and what it lacks as a guarantor of world security: these abutting themes are shaped into a brief, to-the-point essay which concludes with recommendations for turning precarious world interdependence into a cooperative world structure. The US, Belgian diplomat Cassiers reiterates, must balance restraint toward the USSR with firmness (""Some show of power will probably have to be made from time to time in order to. . . put limits on what amounts to retreat""). The developing nations, an international proletariat, are entitled to ""some kind of association providing them with a bargaining position analogous to that enjoyed by trade unions in domestic economies."" And Europe--Cassiers' main concern--should forego dependence on American protection and move toward an integrated European Defense Community confident of its ability to resist outside pressures, capable of influencing the superpowers and ""bridging the psychological gap between the more powerful and the discontented nations."" A cogent analysis, put forth with refreshing economy and full documentation.