The nrst of the people to be thanked for their help during the composition of this work is Professor I.M. Bochenski, under whom I had the good fortune to study for an extended period of time. Without his help, it is doubtful that this work would have been writt"l1 at all. Among the other professors who helped along the way, I would like to cite in particular Professors A.F. Utz, M.D. Philippe and N. Luyten of the University of Fribourg. Many friends were present at the birth of the ideas contained in this book. By naming K.G. Ballestrem, T.l. Blakeley and M.F. Gagern, I do not want to slight any of the rest. It was A. Spiekermann in Hollinghofen who saw to it that other preoccupations did not rob me of all the time needed for the study of the subject-matter and to the composition of this treatise. Of particular help in getting sources from the libraries of the world were Miss Lifschitz of the Institute of East-European Studies and Mr. Uldry of the Cantonal Library in Fribourg, Switzerland. Finally, my patient typist, Mrs. Frey in Munster, deserves special mention for her beautiful work.