PROFESSOR LAZARSFELD ONCE REFERRED TO SOCIOLOGY AS BEING IN A sense a residuary legatee, the surviving part of a very general study, out of which specializations have successively been shaped.The same might be said of political science. In the West the first deliberate and reflective studies of political life were made in Greece at the end of the th century BC, and in the succeeding century. The histories of Herodotus and Thucydides, some of the pamphlets attributed to Xenophon, above all the normative and empirical studies of Plato and Aristotle were among the direct ancestors of contemporary political science. Parallel examples are to be found in the intellectual history of China, India and Islam. It seems that at certain stages in the development of great societies questions of legitimacy, power and leadership assume supreme importance; and intense intellectual effort, using the best analytical tools available, is devoted to the study of man as brought to a focus in the study of politics.