This monumetal and highly erudite work was written by one of the most influential political scientist, comparativist and social science methodologist of the 20th century Giovanni Sartori (1924-2017). The book, consisting of two parts ("The Contemporary Debate" & "The Classical Issues"), provides critical scrutiny of various meanings of democracy since antiquity as well as review of the major democratic theories of our times together with all relevant concepts (such as totalitarianism, authoritarianism) and important methodological issues in the study of politics. Sartori synthesizes a theory of his own emphasizing that in the study of politics ideals (the ought) and facts (the is) have to be related in feedback fashion. The clarity and dramatic power of this work makes it a must read for anyone interested in politics.