The complexity of the calendar of Kemet does not permit a full treatment of it here except to mention a few important points. The Rama ni Kuma concept of time involved cycles that reached beyond centuries, into eras. Essentially, there were two calendars used simultaneously, one can be called the seasonal year of 365 and one fourth days, which was based on Sepdit’s heliacal cycle (also called the Sothic Cycle), and the shifting, or civil year of 365 days. With these two calendars a great year of 1,460 years was derived.
The civil year started its New Year’s Day one day earlier than the seasonal year for every four years of time that passed. It would then take approximately one great year of about 1,460 years (365 x 4) for the two calendars to have the same New Year’s Day again. The Rama ni Kuma used this calendar since the beginning of the dynastic period. This indicates they had the knowledge of these cycles well into pre-dynastic times to make the kinds of observations of stellar and seasonal cycles necessary for its creation.
The method of marking time for the civil year was not based on impractical, stubborn tradition. It measured days more precisely than the seasonal year. It had a practical function since it had 12 months of 30 days each giving it 360 days annually. This allowed for the distribution of materials from granaries by 360, which is conveniently divisible by many numbers. There were five intercalary days added later to match the true length of the year. Thus the 365 day year was important for the administration of the country, which is why it was a civic calendar. With its saint days and Lunar feast days, it had a religious purpose as well. While the true length of time was known to them, each new pharaoh did not adjust the civic calendar to coincide with the seasonal year. The observance of the precise time of the Nile’s inundation was solely in the priests’ hands, as it was their duty to plan for the most important event of the year.
While complicated, this arrangement is highly scientific and it combines knowledge of the seasonal year based on a stellar cycle and seasons, with the shifting civic year. The Rama ni Kuma knew how far on the stellar cycle they were. They knew that the calendar based on Sepdit’s heliacal rising was slightly longer than the year based on the Summer Solstice. This gave them the knowledge of the natural, or solar length of the year as well.
When Julius Caesar wanted to simplify and correct the Roman calendar, which was a lunar one, he was advised by a scientist from Alexandria, Sosigenes. The resulting Julian Calendar was based on the 365 and one fourth day calendar of Kemet. Our present calendar combines some of these concepts of time also, but it is a faint echo of the sense of time the Rama ni Kuma had.
However, it should be noted that the Rama ni Kuma calendar became too complicated with so many cycles merged into its body. At times it is difficult for archeologists to know which calendar dates were used on some monuments. The Kemetu did not date their calendars relative to a specific time such as BC or AD, or the “Common Era”, nor did they use segments of time such as centuries and dynasties is a convenient modern concept.
Beginning in the Middle Kingdom, they related calendrical time by the reign of the pharaoh. Thus, January 4, 2001 would be considered year 9, month 1, day 4 of President Clinton by the civic calendar’s reckoning. There was a more elaborate formula that included the year, month of the season, day in that order, and the throne name of the pharaoh, such as “Year 10, 1 month of Inundation , 6th day, during the incarnation of the King of Upper and Lower Kemet, User- MAat-Re” (Ramses the Great).
The Rama ni Kuma used the heliacal rising of the 36 decans to observe the progress of time during the course of the year, as well as to mark passage of the hours during the night. The 36 decans originally marked the sky at approximately 10 degree intervals each. Thus the heliacal rising of a decan star or stars would span a 10 day period, which are often referred to as the Rama ni Kuma week. This gave each month 3 decan-weeks, and they were sometimes written in hieroglyphic as “Head 10-day period” for the 1st decan, “Heart 10-day period” for the 2nd decan , and “Tail ten-day period” for the 3rd decan.
During the time when Sepdit’s heliacal rising coincided with the Summer Solstice, it started the yearly cycle of the 36 decans. Because of the precession of the Equinox, the beginning decan was eventually shifted to the succeeding decan-star. Later the culminations of the decan stars were used in place of the heliacal risings. During the Hellenistic period, the 36 decans were adapted into the astrology of the Greeks, with a slightly different definition.
Would changes in the locations of the stars brought about by the precession of the equinoxes have caused the Rama ni Kuma to make distinctions between sidereal and tropical cycles? Could the battle between the god Set, who represented not merely evil, but the circumpolar stars, and the god Heru [the Sun], been symbolic of these two cycles of the sky? One was shifting, dark, and distant, the other constant, bright, and life-giving.
They may not have seen the need to distinguish between the cycles, just as they would not have seen the need to draw distinctions between astrologers and astronomers. It was more practical to combine the new adjustments within the traditional scientific and ceremonial practices. That is how their calendar evolved. It is possible astrology will always have to make adjustments, with the battle between Heru and Set bringing renewal.