Founder and first director of the Center for Strategic Analysis at the Ministry of Foreign Affairs of France, founder and director of the French Institute of International Relations, professor of economics, member of the Academy of Moral and Political Sciences, Thierry de Montbrial sets out in his book the foundations of praxeology. This is the science of action, which is most often collective, aimed at changing some part of the world in favor of a certain active unit. The totality of the actions of active units determines the course of the History of the fate of people. Praxeology is explained in the book as general principles and specific examples of their application. Special attention is paid to two complementary areas - economics and international relations. It is explained how international relations in a world divided into conflicting political units form one of the fundamental categories of praxeological problems. Known for his vast erudition and excellent training in mathematics, Thierry de Montbrial constantly tries to find existing and possible bridges between the exact sciences and the humanities. In December 2006, Thierry de Montbrial was elected a foreign member of the Bulgarian Academy of Sciences.