What most facilitated the centralisation under the imperial rule was of course the imported Chinese civilisation. To say sooth, several centuries of the slow infiltration of that high civilisation had already attained a great deal of influence, but it was rather a smuggled, and not a really legalised importation. Moreover, China herself, the source from which the civilisation had to be imported, had been dismembered for a long time, so that until 581 A.D. the country could hardly be called a unified state at all. How could we expect to find in a country where no order ruled a model suitable to be employed as exemplar to effect a durable political reform. It is not strange, therefore, that, notwithstanding the long years of intercourse between the two countries, only a very slight change had been thereby occasioned in our country as regards our political organisation. Any change which was wrought in our political sphere by Chinese influence was effected in a very indirect way, having worked its way through multifarious social changes caused by the contact with the high alien civilisation. No direct political clue could be followed up from China to this country. To achieve the purpose of borrowing from China the necessary materials for the reconstruction of political Japan, we had to wait longer, that is to say, till the inauguration of regular intercourse between this country and China also politically unified and concentrated. That memorable year came at last. In 607 A.D. Ono-no-Imoko was despatched as official envoy to China, which at that time was under the second emperor of the dynasty of Sui. Even before this date, however, since the accession of the Empress Suiko, as the result of the busy intercourse between us and the peninsular states, various arts and useful sciences of Chinese origin had been introduced into this country, among which astronomy, the oldest perhaps of all sciences everywhere in the world, was the most noteworthy. Connected with this science, the art of calendar-making was introduced for the first time into Japan. It would be a gross mistake, if we thereby conclude that we had no means of defining the dates of events prior to this introduction. Although we could not by ourselves make an independent calendarial system, yet the Japanese, at least the naturalised scribes, had already been acquainted with two chronological methods. The one was to define a date by counting from the year of the accession of a reigning emperor. The other method was that which had prevailed long since in China, that is to say, to define a date by counting according to the cyclical order of the twelve zodiacal signs, interlaced with the cyclical order of ten attributes, so that to complete one cycle sixty years were necessary. Some groups of scribes, perhaps, pursued the former method, while others favoured the latter. Contradictory statements and evident repetitions abundantly found in the _Nihongi_ were thus occasioned by the existence of