Book excerpt: to Seeking the answer to the three basic questions of contempo rary private international law, I also deemed it essential to out line to the reader the historical development of the different concepts of this particular branch of law, for without the know ledge of this history it is impossible to understand the contempo rary problems. The fact that private international law oscillates between public international law and substantive municipal law as it is applied in individual countries creates considerable problems in both theory and practice. I have tried to deal with these problems in the third part of my study, concerning "universa lism" and "nationalism" in the doctrine of private international law, as well as in its fourth part, which is devoted to the object and nature of this law and its place in the overall system of law. The character of private international law, ensuing from the plurality of municipal laws - which also characterize the origin and existence of comparative jurisprudence - in spired me to produce the fifth part of this study, which prima rily tries to expJain the theoretical problems of comparative jurisprudence but does so - defining its objectives and possibili ties - in order to underline at the same time its role in private international law and in the law of international trade.