WHICH RULE GOVERNS THE ORDER OF THE DAYS OF THE WEEK IN ARTIFACTS FROM THE ROMAN AGE TO THE 17TH CENTURY?

I show in the present work some artifacts from the Roman Era up to the 17th century related to the name of the days in a critical way. In each of them there are the 7 planetary Gods of Mediterranean culture related to the days of the week, and I discuss the enigmatic question of their order. Which rule do the planets follow so that the day of the Sun (Sunday) is followed by the day of the Moon (Monday) and so on? What did people know about the 7 planets? When was the time unit of the week established? In the end, we explore their harmonious and cyclic spatial arrangement. Moreover, in different languages the names of the 7 planets refer to different gods. In the ancient Roman world another system preceded it: nundinae, linked to market days and not to the sky. The studied artifacts are calendars, painted or engraved on marble tables, mosaics and bas-reliefs, Planetary tables published in medieval texts and two artefacts of the 17th century.