A hallmark of almost every known culture is some system to track the passing of time. It is thought that, like most agricultural societies, the ancient Egyptians originally organized their calendar according to the cycles of the moon and the agricultural seasons (30.4.2). Most scholars agree that the Egyptian day began at dawn, before the rising of the sun, rather than sunrise. The daily cycle was divided into twenty-four hours: twelve hours of the day and twelve hours of the night, the latter apparently reckoned based on the movement of groups of stars (“decans”) across the night sky. Beginning in the New Kingdom (ca. 1500 B.C.), there is evidence that sundials, shadow clocks (12.181.307), and water clocks (17.194.2341) were used to measure the passing of the hours. There is no evidence that the Egyptians tracked minutes or seconds, although there are general terms for time segments shorter than an hour. The month was organized into three weeks of ten days each, with the start of the lunar month marked by the disappearance of the waning moon.
By at least the middle of the Old Kingdom (ca. 2450 B.C.), and quite possibly several centuries earlier, the Egyptians had developed a “civil” calendar composed of twelve months of thirty days each (360 days), divided into three seasons—Inundation (Akhet), Emergence (Peret), and Harvest (Shemu)—of four months each, with five epagomenal days (days outside the regular months) added at the end of the year. Official dates were expressed according to this system, as a specific day within a specific month of a season (e.g., Day 15, Month 3 of the Inundation Season). At least as early as the Middle Kingdom (ca. 2030–1650 B.C.), the months had alternative names (22.3.522) that seem to echo some sort of lunar reckoning.
It is likely that New Year’s Day (30.8.214) originally was associated with the heliacal rising of the brightest star in the night sky, Sopdet (also known by its Greek name of Sothis or Latin name of Sirius). In Egypt, this star reemerged after a seventy-day sojourn beneath the horizon at about the same time as the first signs of the annual Nile flood that brought the life-giving waters down from the highlands of Ethiopia. The correlation between Sopdet and the New Year is based in part on an ancient text (from ca. 2500 B.C.) that reads: “It is Sopdet, your daughter whom you love, in this her name as Year”; an inscription from the New Kingdom that mentions the rising of Isis-Sopdet on the morning of New Year’s Day (ca. 1250 B.C.); and a reference to Isis-Sopdet from the much later temple at Dendera (late first millennium B.C.), which says specifically that the years are “reckoned from her shining forth.”
Since a true astronomical year has 365.25+ days, the Egyptian civil calendar fell back by a quarter day or so each year. This meant that the rising of Sopdet/Sothis and the seasons of this calendar did not correspond to the actual agricultural seasons for much of Egyptian history. Scholars have attempted to use this disconnect, especially between the actual Sothic rise and New Year’s Day in the civil calendar, which correspond only once every 1,460 years, to calculate when the civil system was first established, but no agreement on this point has yet been reached.
Lunar-based month names, the importance of the heliacal rising of Sothis, the fact that some Egyptian festivals were scheduled according to the lunar cycle rather than tied to specific days in the civil calendar, and some double dates, have led scholars to posit an early luni-stellar calendar that would have operated alongside the civil calendar. This presumably would have been corrected regularly (perhaps by adding a thirteenth month or an extra epagomenal day every several years) to stay in step with the actual astronomical year (66.99.73).
Although the exact format changes over time, years were for the most part counted according to the reign of a specific ruler (10.176.42; 09.184.183). In Dynasty 1 (ca. 3100 B.C.), each civil year within a reign was identified by important events such as the founding of a temple or the installation of a cult statue, a practice that lasted well into the Old Kingdom (ca. 2649–2130 B.C.). It is also during Dynasty 1 that the germ of a system to number the years by reign appears, in a record of “the first occasion of the Djet (“eternity”)-festival,” probably referring to the first time this festival had been celebrated during the reign of King Djer. By late Dynasty 2 (ca. 2900 B.C.), regnal years were being labeled according to the apparently biennial census of the country’s mineral, animal, and/or agricultural assets. This soon seems to have become the key event by which years were counted: through to the end of the Old Kingdom (ca. 2130 B.C.), years can be named as either renpet zep N (Year of the Nth Counting) or renpet em-khat zep N (Year after the Nth Counting). Scholars long assumed that these counts were always biennial, and that minimum reign lengths for Old Kingdom monarchs could be estimated by doubling the highest attested census. However, recent scholarship has begun to question this construct and to suggest alternatives such as biennial counts that gradually became annual; counts carried out as needed to raise funds for government projects; or counts carried out in years during which a thirteenth month was added to the theoretical luni-solar calendar. It seems likely that annual counts became the rule by Dynasty 6 (ca. 2323–2150 B.C.), but overall, this question remains open.
At some point, most likely during the First Intermediate Period (ca. 2130–2030 B.C.), years began to be numbered according to each king’s tenure on the throne. During the Middle Kingdom (ca. 2030–1650 B.C.), these years were counted from one New Year’s Day to the next; the period of time between the new king’s coronation and Day 1 of Month 1 may have been counted as his Year 1, but alternatively may have been left to his predecessor. In the New Kingdom (ca. 1550–1070 B.C.), the regnal count began when the new king took the throne, and years were calculated from one anniversary of the coronation to the next (50.6) all according to the civil calendar. It is likely that the same system pertained during the Third Intermediate Period (ca. 1070–664 B.C.). During the Late Period (ca. 664–332 B.C.), the second option outlined as a possibility for the Middle Kingdom was in use: the king’s Year 1 was counted from coronation to New Year’s Day, and his Year 2 began with the new year, so that a Year 1 could last anywhere from a week to almost a year.
Also extremely important in the ancient Egyptian conception of the world was their larger attitude toward time. Inscriptions refer to two kinds of eternity. Linear time, or djet, associated with the funerary god Osiris (56.16.2), had a beginning and would have an end, albeit in the infinitely far future. Neheh, cyclical time, was tied to the passage of the sun through the sky during the day and the Netherworld during the night (O.C.81). Ideally, an Egyptian who had lived according to the precepts of maat by supporting and maintaining the proper order of a just cosmos, and who had been accorded a proper burial, would live forever (djet) and ever (neheh).