A Wonder Why, Ever Wonder Why There Are Seven Days a Week

A Wonder Why…

Ever Wonder Why There Are Seven Days a Week

The number of days in the week has not always been 7 in all societies. The early Egyptians had a 10 day week, as did briefly the French Revolutionary Government two hundred years ago. An ancient calendar once used in Lithuania employed a 9 day week, whilst the Mayans of Central America used a complicated system including ‘weeks’ of 13 numbered days and ‘weeks’ of 20 named days. As recently as 1930, the Soviet Union toyed with the idea of a 5 day week.

The point about this is that a week – unlike a year (one complete revolution of the Earth around the Sun), or a day (one complete rotation of the Earth on its axis) – has no scientific basis; there is no astronomical event pertaining to a week, much less a week of 7 days.

However the number 7 did hold a sacred significance for many societies in which ritual was of great importance. The lunar month was approximately 28 days long (easily divisible into four quarters or phases of the moon, each of 7 days), and in the sky there were 7 traditionally identified planets. Both of these factors contributed at different times to the adoption and proliferation of the 7 day week as we shall see. Later on the 7 day creation myth of the burgeoning Christian religion cemented the length of the week in most Western civilisations,

It seems that ancient Babylon was possibly the first civilisation to divide the year in this way, and it seems it was the length of the lunar month which was most important to this society. The phases of the lunar cycle – New Moon, waxing half Moon, Full Moon, and waning Half Moon – were obvious visual signs which could be interpreted in a religious or astrological way. Certain activities and festivals became set by the phases of the Moon, and hence by the days of a 7 day week.

This was later adopted by the Greek and Roman Empires, and then the Christian religion. As Christian European nations developed empires throughout the world, so the 7 day week became the established norm.