The separation of a caste entrusted with the social responsibility of regulating the seasonal pursuits of a settled agrarian economy marks the beginning of written history. Only at this point does the need for a permanent record of events and measurements emerge. Here, also, we see history repeating itself -- or if you prefer it -- history at a standstill in backward cultures of the present day. Speaking of the time-keeping function of the priesthood in contemporary societies, Nilsson says:
As long as the determination of time is adjusted by the phases of Nature which immediately become obvious to everyone, anybody can judge of them, and should different people judge differently there is no standard by which the dispute can be settled, because the natural phases run into one another or are at least not sharply defined. The accuracy in determination demanded by time-reckoning proper is therefore lacking. Accuracy becomes possible as a result of the observation of the risings of stars, and this observation begins even at the primitive stage, but it is not a matter that concerns everyone. It requires a refined power of observation and a clear knowledge of the stars, so that the heavens can be known. This is especially the case with the commonest observations, those of the morning rising and evening setting. The observer must be able to judge, by the position of the other stars, when the star in question may be expected to twinkle for a moment in the twilight before it vanishes. The accuracy of the time-determination from the stars depends therefore upon the keenness of the observation. In this the individual differences of men soon come into play, along with a regular science which introduces the learner to the knowledge of the stars and its uses. Thus Stanbridge reports of the natives of Victoria that all tribes have traditions about the stars, but certain families have the reputation of having the most accurate knowledge; one family of the Boorung tribe prides itself upon possessing a wider knowledge of the stars than any other. . . . By the phases of the stars both occupations and seasons are regulated, and thus a standard is furnished by which to judge, and a limit is set to the indefiniteness of the phases of Nature. . . . The moon strikes the attention of everyone and admits of immediate and unpractised observation; at the most there may sometimes be some doubt for a day as to the observation of the new moon, but the next day will set all right. But because the months are fixed in their position in the natural year through association with the seasons, the indefiniteness and fluctuation of the phases of Nature penetrate into the months also, and are there even increased, for the reasons stated above. Cause for doubt and disagreement is given, the problem of the regulation of the calendar arises. Hence in the council meetings of the Pawnee and Dakota it is often hotly disputed which month it really is. So also the Caffres often become confused and do not know what month it is; the rising of the Pleiades decides the question. The Basuto in determining the time of sowing are not guided by the lunar reckoning, but fall back upon the phases of Nature; intelligent chiefs, however, know how to correct the calendar by the summer solstice. . . . The differences in intelligence already make themselves felt at an early stage, and are still more plainly shown when we come to a genuine regulation of the calendar. Some of the Bontoc Igorot state that the year has eight, others a hundred months, but among the old men who represent the wisdom of the people there are some who know and assert that it has thirteen. The further the calendar develops, the less does it become a common possession. Among the Indians, for example, there are special persons who keep and interpret year-lists illustrated with picture-writings, e.g. the calendrically gifted Anko, who even drew up a list of months. It is very significant that even where a complete calendar does exist, it will be found that this is not in use to its fullest extent among the people. . . . It follows that the observation of the calendar is a special occupation which is placed in the hands of specially experienced and gifted men. Among the Caffres we read of special "astrologers." Among the Kenya of Borneo the determination of the time for sowing is so important that in every village the task is entrusted to a man whose sole occupation it is to observe the signs. He need not cultivate rice himself, for he will receive his supplies from the other inhabitants of the village. His separate position is in part due to the fact that the determination of the season is effected by observing the height of the sun, for which special instruments are required. The process is a secret, and his advice is always followed. It is only natural that this individual should keep secret the traditional lore upon which his position depends; and thus the development of the calendar puts a still wider gap between the business of the calendarmaker and the common people. Behind the calendar stand in particular the priests. But they are the most intelligent and learned men of the tribe, and moreover the calendar is peculiarly their affair if the development has proceeded so far that value is attached to the calendar for the selection of the proper days for the religious observances. Among the priests there is formed a special class whose duty, it is to make observations and keep the calendar in order. Among the Hawaiians "astronomers (kilo-hoku) and priests" are mentioned; they handed down their knowledge from father to son; but women, kilowahine, are also found among them. Elsewhere the nobles appear alongside of the priests; thus in Tahiti it is the nobles who are responsible for the calendar, in New Zealand the priests. In the latter country there is said to have been a regular school, which was visited by priest and chiefs of highest rank. Every year the assembly determined the days on which the corn must be sown and reaped, and thus its members compared their views upon the heavenly bodies. Each course lasted from three to five months.