Questions and answers about the Calendar


Who invented the week?

The Sumerians and Babylonians did. It is an arbitrary invention, although (AB:) probably invented as a useful subdivision (1/4th) of the lunar month, lasting approx. 28 days. The Sumerians and the Babylonians divided the year into weeks of seven days each, one of which they designated a day of recreation. So perhaps it is a basic human necessity to rest one of every 7 days which gives a fundamental character to the length of a week. The Jews adopted their calendar from the Babylonians during their stay there after the destruction of the Temple.


Who invented the month?

The month was already in use by the Babylonians, and is derived from the word for Moon. The Hebrew words for moon and month are the same. It is the time it takes for a lunar phase cycle (roughly the time of the Moon's translation around the Earth, corrections to convert that into phase cycle take into account translation around the Sun, the illuminator).


Who invented the year?

The year, the time it takes for the Earth to go around the Sun, was already used to count time by the Babylonians, who originally had two seasons (enough in that area), but who had 3 or 4 seasons in more northern areas. The Jews called the start of the year by when the ears of barley were ready.


Where do the names of the weekdays come from?

The Babylonians named each of the days after one of the five planetary bodies known to them and after the Sun and the Moon, a custom later adopted by the Romans. For a time the Romans used a period of eight days in civil practice, but in AD 321 Emperor Constantine established the seven-day week in the Roman calendar and designated Sunday as the first day of the week. Subsequent days bore the names Moon's-day, Mars's-day, Mercury's-day, Jupiter's-day, Venus'-day, and Saturn's-day. Constantine, a convert to Christianity, decreed that Sunday should be a day of rest and worship.

The days assigned by the Romans to the Sun, Moon, and Saturn were retained for the corresponding days of the week in English (Sunday, Monday, and Saturday) and several related languages. The other weekday names in English are derived from Anglo-Saxon words for the gods of Teutonic mythology.


Where do the lengths of months come from? And the leap year? Why is it called bisiesto in Spanish?

From Julius Caesar's time. In the mid-1st century BC Julius Caesar invited Sosigenes, an Alexandrian astronomer, to advise him about the reform of the calendar, and Sosigenes decided that the only practical step was to abandon the lunar calendar altogether. Months must be arranged on a seasonal basis, and a tropical (solar) year used, as in the Egyptian calendar, but with its length taken as 365 1/4 days.

The figure of 365.25 days was accepted for the tropical year, and, to achieve this by a simple civil reckoning, Caesar directed that a calendar year of 365 days be adopted and that an extra day be intercalated every fourth year. Since February ordinarily had 28 days, February 24 was the sixth day (using inclusive numbering) before the Kalendae, or beginning of March, and was known as the sexto-kalendae; the intercalary day, when it appeared, was in effect a "doubling" of the sexto-kalendae and was called the bis-sexto-kalendae. This practice led to the term bissextile being used to refer to such a leap year. The name leap year is a later connotation, probably derived from the Old Norse hlaupa ("to leap") and used because, in a bissextile year, any fixed festival after February leaps forward, falling on the second weekday from that on which it fell the previous year, not on the next weekday as it would do in an ordinary year.
These arrangements for the months can only have remained in force for a short time, because in 8 BC changes were made by Augustus. In 44 BC, the second year of the Julian calendar, the Senate proposed that the name of the month Quintilis be changed to Julius (July), in honour of Julius Caesar, and in 8 BC the name of Sextilis was similarly changed to Augustus (August). Perhaps because Augustus felt that his month must have at least as many days as Julius Caesar's, February was reduced to 28 days and August increased to 31. But because this made three 31-day months (July, August, and September) appear in succession, Augustus is supposed to have reduced September to 30 days, added a day to October to make it 31 days, reduced November by one day to 30 days, and increased December from 30 to 31 days, giving the months the lengths they have today. (this interpretation is in dispute)


Who started numbering days of the month?

The Julian calendar retained the Roman republican calendar method of numbering the days of the month. Compared with the present system, the Roman numbering seems to run backward, for the first day of the month was known as the Kalendae, but subsequent days were not enumerated as so many after the Kalendae but as so many before the following Nonae ("nones"), the day called nonae being the ninth day before the Ides (from iduare, meaning "to divide"), which occurred in the middle of the month and were supposed to coincide with the Full Moon. Days after the Nonae and before the Ides were numbered as so many before the Ides, and those after the Ides as so many before the Kalendae of the next month.


When did weeks go into usage again? Which were festive days?

It should be noted that there were no weeks in the original Julian calendar. The days were designated either dies fasti or dies nefasti, the former being business days and days on which the courts were open; this had been the practice in the Roman republican calendar. Julius Caesar designated his additional days all as dies fasti, and they were added at the end of the month so that there was no interference with the dates traditionally fixed for dies comitiales (days on which public assemblies might be convened) and dies festi and dies feriae (days for religious festivals and holy days). Originally, then, the Julian calendar had a permanent set of dates for administrative matters. The official introduction of the seven-day week by Emperor Constantine I in the 4th century AD disrupted this arrangement.


How did January 1st become the beginning of the year?

It appears, from the date of insertion of the intercalary month in the Roman republican calendar and the habit of designating years by the names of the consuls, that the calendar year had originally commenced in March, which was the date when the new consul took office. In 222 BC the date of assuming duties was fixed as March 15, but in 153 BC it was transferred to the Kalendae of January, and there it remained. January therefore became the first month of the year, and in the western region of the Roman Empire, this practice was carried over into the Julian calendar. In the eastern provinces, however, years were often reckoned from the accession of the reigning emperor, the second beginning on the first New Year's day after the accession; and the date on which this occurred varied from one province to another.


How did Pope Gregory XIII modify the Calendar to that which we use currently?

The Julian calendar year of 365.25 days was too long, since the correct value for the tropical year is 365.242199 days. This error of 11 minutes 14 seconds per year amounted to almost one and a half days in two centuries, and seven days in 1,000 years. Once again the calendar became increasingly out of phase with the seasons.

By 1545, however, the vernal equinox, which was used in determining Easter, had moved 10 days from its proper date; and in December, when the Council of Trent met for the first of its sessions, it authorized Pope Paul III to take action to correct the error. Correction required a solution, however, that neither Paul III nor his successors were able to obtain in satisfactory form until nearly 1572, the year of election of Pope Gregory XIII. Gregory found various proposals awaiting him and agreed to issue a bull that the Jesuit astronomer Christopher Clavius (1537-1612) began to draw up, using suggestions made by the astronomer and physician Luigi Lilio (also known as Aloysius Lilius; died 1576).

To bring the year closer to the true tropical year, a value of 365.2422 days was accepted. This value differed by 0.0078 days per year from the Julian calendar reckoning, amounting to 0.78 days per century, or 3.12 days every 400 years. It was therefore promulgated that three out of every four centennial years should be common years, that is, not leap years; and this practice led to the rule that no centennial years should be leap years unless exactly divisible by 400. Thus, 1700, 1800, and 1900 were not leap years, as they would have been in the Julian calendar, but the year 2000 will be.




Are Jews allowed to fight on the Sabbath?

In Maccabean times (2nd century BC) observance of the Sabbath was so strict that the Jews allowed themselves to be slaughtered on that day rather than take up arms to defend themselves. Realizing that such an attitude could mean their extinction, the Jews determined to fight if attacked again on the Sabbath. The Talmud sanctioned this decision and said that 39 general categories of forbidden works were suspended when life or health were seriously endangered, for "the Sabbath was given to man, not man to the Sabbath."


This page has been visited times.

Back to Alex Bäcker's Publications.