In ancient times, the concepts of "week" and "days of the week" did not exist. it was too difficult to give each day its own name. However, with the development of cities, it became necessary to designate certain days for rest, trade, and religious customs. Sometimes, for specific purposes, every tenth day, or the fifth or seventh day, was appointed.
The first mention of a week of seven days dates back to 2000 BC. It was the seven-day time frame that was invented in Ancient Babylon, and it became the most convenient combination of days, in which the last, seventh day is a day off. Ancient Babylonian astronomers identified seven days of the week according to the change in the phases of the moon, besides, the number "7" has been considered sacred and endowed with special powers since ancient times.
From Babylon, this tradition passed to the Jews, Greeks, Egyptians, Romans. The Jews set aside every seventh day as a religious day. And the Egyptians and Romans named the seven days of the week after the names of the planets. Jews and Christians believed that the seven-day time structure was established by God. All this because the Old Testament says that on the first day of creation light was created, on the second - water and firmament, on the third - seas, land, vegetation, on the fourth - heavenly bodies, on the fifth - the animal world, on the sixth - man. and finally, on the seventh day, it was called to rest.
The names of the days of the week in the languages of the Latin group are very similar. For example, Monday is Moon Day: Monday in English, Lundi in French, el Lunes in Spanish.
In the names of Tuesday, the name of the god Mars is hidden: Dies Martis - in Latin, Mardi - in French, el Martes - in Spanish, Martedi - in Italian. And in other languages of this group the name of the ancient German god Tiu is hidden, the same warlike as Mars - Tiistai - in Finnish, Tuesday - in English, Dienstag - in German.
Mercury is easily guessed in the names of the environment. Dies Mercuri - in Latin, le Mercredi - in French, in Italian - Mercoledi, in Spanish - el Miercoles. In other languages, you can see that the name comes from the name of the god Voden, who invented the runic alphabet, this fact can be attributed to the fact that Mercury is the patron god of speech and writing. Thus, Wednesday is Wednesday in English, Onstag in Swedish, Woenstag in Dutch.
Thursday is the day of Jupiter, in Latin it is Dies Jovis. Hence, Jeudi is Thursday in French, Jueves in Spanish, Giovedi in Italian. And other names have a connection with the god Thor: English Thursday, Torstai - in Finnish, Torsdag - in Swedish.
The name of Friday immediately shows the influence of Venus. French Vendredi, Italian Venerdi, Spanish Viernes. And the English Friday, Swedish Fredag and German Freitag originated from the name of the Scandinavian goddess of love and fertility Freya (Frigge).
The image of Saturn is immediately visible in the names of Saturday: Saturday in English and Saturni in Latin. Finnish Lauantai, Swedish Lördag and Danish Loverdag are similar to the ancient German Laugardagr and mean "ablution day", which means that traditionally Saturday is a bath day.
In the names of the resurrection there is an image of the Sun, various variations of Sun / Son. But there is another origin of the names - Lord's Day, this can be traced in Spanish - Domingo, French - Dimanche and Italian - Domenica.
In Russia, the names were formed according to a different principle. The week was called the week. Monday is literally "day after week". Tuesday, the name speaks for itself - the second day of the week. Wednesday got its name as the average day of the week, but this, if you count, is not quite like it is now: before the week began on Sunday, and then Wednesday took its rightful place. In the Old Russian language, the name of the environment is still found as "third party". Thursday, like Tuesday, is named by its ordinal number, the fourth day. The same story with Friday - the fifth day of the week. The Sabbath comes from the Hebrew sabbat / sabbath, which means the last working day of the week, the end of all things. Sunday used to be called "week" ("no work", "do not do"), and with the advent of Christianity it was renamed in honor of the Day of the Resurrection of Jesus Christ.