For many centuries, people have observed changes in nature, identified patterns that later formed the basis of calendars. This word translated from Latin (calendarium) means "debt book". On the first day of the month, debtors in ancient Rome paid interest in the form of calendars. The modern meaning of the word "calendar" appeared in the Middle Ages - it is a system for counting periods of time, based on the apparent motions of the Sun and the Moon.
The division of the year into twelve months took place in ancient Rome during the reign of Julius Caesar. Prior to this, the year was divided into ten months and began with March, named Marius in honor of the god Mars, the patron saint of field work that began that month. Next came April; its name comes from the Latin word aperire, which means "to unfold." May is named after the goddess of fertility Maya, and June is named after Juno. All subsequent months: Quintilis, Sextilis, September, October, November, December denoted a serial number. 46 BC. on the advice of the Egyptian court astrologer Sozigen, Julius Caesar carried out a calendar reform. He immortalized himself by renaming the month of Quintilis to Julius, and added two more months to the year - January and February. The first was named after the two-faced god of all beginnings Janus, and the second means "cleansing of the year." At the same time, a four-year solar cycle was established: three years of 365 days and one with 366 days. The months began to have unequal lengths: 30 days each in April, June, Sectyabr, September and November; 31 days each in January, March, May, July, October and December; and 29 days in February. Every fourth year, an additional day was inserted before the March calendars. The beginning of the year was postponed from March to January, it was in this month that the economic year in Rome began, and the consuls took office, and the emperor Octavian Augustus completed the reform, giving the month Sextilis his name. Not wanting to put up with the fact that "his" month is one day shorter than Julius, he added one more day to August, taking it away from February. Since that time, in February, three years of the cycle are 28 days, and in the fourth - 29. In ancient Russia, the calendar year was divided into four seasons. There was also a lunisolar calendar with the inclusion of seven additional months every 19 years. With the adoption of Christianity, the account began to be kept according to the Byzantine version of the Julian calendar, albeit with some deviations. According to the tradition in Russia, the year still began in March. In 1492, Ivan III postponed the beginning of the year to September 1, and in 1699, by decree of Peter I, the chronology "from the creation of the world" was replaced by the Julian calendar with the beginning of the year on January 1.
