Emergence of Calendar
The calendar was born from the necessity of ordering the activities of human beings. As societies shifted from primitive hunting cultures to agriculture, people began to produce, harvest, and store food systematically based on seasonal changes of the climate.
In around 3000 B.C., the Egyptians observed that Sirius started blinking in the east sky every year before the Nile flooded over during the rainy season in early summer. They created the “Sirius Calendar (Egypt Calendar),” the original solar calendar, by marking the middle day of summer as the first day of a year, and setting a year as the 365 days that passed until Sirius appeared in the sky again. Their year was composed of twelve months of 30 days, each based on the lunar cycle, plus five Sabbath days at the end of the year. A year was also divided into three four-month seasons based on this calendar: the season of floods, the season of seeding, and the season of harvesting.
Reform of the Calendar
Julius Caesar introduced “the Julian Calendar” in 46 B.C. in Rome. His calendar was based on the solar calendar of Egypt, with an extra day added to every fourth year, leap year, to correct the error. The Julian calendar spread throughout Europe.
After the Julian calendar had been used for about 1600 years, natural philosophers deduced that it gained one day every 128 years. To recover the authority of Christianity, Pope Gregory XIII corrected the 13-day error accrued since Caesar’s time and introduced “the Gregorian calendar.” The Gregorian calendar is still used around the world today.
The Gregorian calendar was defined as follows: a year divisible by four is a leap year, but a year divisible by 100 but indivisible by 400 is not a leap year.
The calendar symbolized the great power of the Pope who introduced it.
Since ancient times, human beings have been fascinated by the changing phases of light and darkness from the waxing and waning of the moon and the repetitive cycle of light and darkness with the rising and setting of the sun. Before modern illumination, people lived largely by moonlight at night.
The Babylonians are believed to have been the first to notice that the transitions of the seasons were brought by cycles not only in the positions of the sun in the sky, but also the waxing and waning of the moon. The so-called lunar calendar was based on this observation.
The moon revolves around the earth once every 29.5 days, or one lunar month. One lunar calendar year of twelve months becomes 354 days, or 11 days less than the actual solar calendar year based on the revolution of the earth. The lunar calendar was unsuitable for farming, because days based on the moon and seasons based on a 365-day year varied from year to year.
Hijri (Hegira) Calendar in Islamic Society
The Hijri calendar based on the lunar calendar (the Mahomet calendar) is still used in many Islamic societies to celebrate festivals such as Ramadan and Hadj. The first day of the Hijri calendar was set on what they regarded as the 622nd year of the Julian calendar, when the Islamic prophet Mahomet (Muhammad) escaped from Mecca to Medina (called Hijri). Islamic people still strictly follow this historic calendar for religious events.
The Babylonians are said to have started using a lunisolar calendar by no later than 2000 B.C. This calendar was adjusted by adding a leap month to the 354-day lunar year based on the lunar cycle to account for climatic changes based on the solar cycle in a 365-day year.
The lunisolar calendar was completed somewhere in or around the Neo-Babylonian Empire and spread to almost all regions of the Eurasian Continent except Egypt. At one point it was passed on to a Jew imprisoned in a Babylonian jail, who went on to introduce it to his tribe. The current Jewish calendar is one of the few remaining calendars based on the lunisolar calculations.
Almost all nations and regions of today’s world use the Gregorian calendar. The lunisolar calendar is mostly unused.
According to inscriptions on bones and tortoise carapaces from the Yin era, the Chinese were probably using a calendar counted by the sexagenary cycle based on the lunar calendar by around 1500 B.C. Some 2000 years ago, the Chinese stipulated 24 solar terms to correct the gap between the calendar and the seasons. One seasonal month was about 30 days, longer than one lunar month. The Chinese started to use a lunisolar calendar in which each seasonal month was adjusted by increasing the number of leap months. They continued using this calendar until 1912, when the Republic of China was established.
The Chinese and almost all of their neighbors on the Eurasian continent continued using the lunisolar calendar for much longer than anyone else. The lunisolar calendar was useful for closely tracking tides and waxing and waning of the moon in order to predict floods in the great river basins and to forecast marine conditions for fishermen in coastal areas.
Calendar in Japan
The Japanese of ancient times lived without a well-trusted calendar. They were believed to have relied on a natural calendar following natural phenomena instead. Their first calendar was probably adopted in 690, when the lunisolar calendar came from China. For more than eight-hundred years from 862, the Japanese people used the Senmyo Calendar. Next, from 1685, they used the Japanese Jyokyo Calendar, a corrected variant of the Senmyo Calendar, invented inside Japan. Several other Japanese invented original calendars based on the lunisolar calendar in ensuing years. Japan reformed its calendar in 1872 and introduced the western Julian calendar in 1873. then Gregorian calendar in 1898.
The Japanese Meiji Government needed to organize its society according to the Gregorian calendar in order to adopt Western systems modeled around Western calendar days. Historians have related an interesting story about the adoption of the new calendar. As the story goes, the government took advantage of the switchover in order to underhandedly save money in a fiscal pinch. The year 1873 was a leap year according to the old calendar, and the government was due to pay its employees an additional month’s salary (salary for a 13th month according to Western customs). Drastically short of funds, the government advanced New Year’s Day by one month without notifying the citizenry in advance. A full month disappeared from the calendar overnight, and with it the obligation to pay the leap month salary.
To put the public at ease, the eminent author Yukichi Fukuzawa wrote an “Explanation of the New Calendar, (Kairekiben)” a famous instruction extolling the advantages of the solar calendar over the lunisolar calendar.
・Hirai, S., Story of Timepieces, Asahi Shimbun Publisher
・Yamaguchi, R., Timepieces, Iwanami Shinsho
・Watanabe, T., All of the Calendar, Yuzankaku