Although in the present study I devote only a few pages to the Greek time-reckoning, and am engaged for the most part in very different fields, yet the work has arisen from a desire to prepare the way for a clearer view of the initial stages of the Greek time-reckoning. In the course of my investigations into Greek festivals I had from the beginning been brought up against chronological problems, and as I widened the circle so as to include the survivals of the ancient festivals in the Middle Ages, more particularly in connexion with the origin of the Christmas festival, I was again met by difficulties of chronology, this time in regard to the earlier Germanic time-reckoning. In the year 1911 I published in _Archiv für Religionswissenschaft_ an article on the presumptive origin of the Greek calendar circulated from Delphi. These preliminary studies led to my taking over myself, in the projected Lexicon of the Greek and Roman Religions, the article on the calendar in its sacral connexions. This article was worked out in the spring of 1914. In it the emphasis was laid not on the historical chronological systems, which have little to do with religion, but on the question of origins, in which religion plays a decisive part. In order to arrive at an opinion it was not enough to work over once more the extremely scanty material for the origin of the Greek time-reckoning; I had to form an idea from my hitherto somewhat occasional ethnological reading as to how a time-reckoning arose under primitive conditions, and what was its nature. This idea obviously required broadening and correcting by systematic research. The war, which suspended the continuation of the Lexicon at its very beginning, gave me leisure to undertake this more extensive research. Certainly it has also imposed some limitations on the work, since I could not make use of the rich libraries of England and the Continent but had to be content with what was offered by those of Sweden and Copenhagen. But I am not disposed to regret this limitation too deeply. The material here reproduced will probably strike many readers as being copious and monotonous enough, and the numerous books of travels and ethnological works which I have ransacked, often to no profit, seem to hold out little prospect that anything new and surprising will come to light. In this conviction Webster’s work has strengthened me. In two or three instances I have derived material of great value from personal communications. For very interesting details of the time-reckoning of the Kiwai Papuans I am indebted to Dr. G. Landtman of Helsingfors, and Prof. G. Kazarow of Sofia has sent me valuable information as to the Bulgarian names of months. Dr. C. W. von Sydow of Lund has communicated to me details of the popular time-reckoning in Sweden.