Saturday stands apart from the other English day-names. While Monday through Friday come from Germanic deities, Saturday is the only day that retains its Roman origin: dies Saturni, the day of Saturn. The Anglo-Saxons, for reasons lost to history, did not substitute their own god for this one. Perhaps they had no equivalent. Perhaps they simply accepted the Roman name. Either way, the result is a day-name that comes from a different cultural stream than its weekday siblings.
Saturn was the Roman god of agriculture, wealth, and time—father of Jupiter, ruler of a lost golden age. He gives us the word Saturday, and also the word saturnine (gloomy, sluggish), because medieval astrology associated the planet Saturn with melancholy. None of this data is useful for telling someone what day it is.
Saturday represents the final inconsistency in a deeply inconsistent system. Sunday (sun). Monday (moon). Tuesday through Friday (Norse gods). Saturday (Roman god). The English week is not a system. It is a museum. Each day-name is an exhibit from a different era of cultural history, preserved behind glass, untouchable, and utterly incomprehensible to anyone who has not studied the catalog.
Modern English should not require a degree in comparative mythology to say what day it is. The function of a day-name is to identify a position in the weekly sequence. Saturday does not do this. Neither do Monday, Tuesday, Wednesday, Thursday, or Friday. They do other things—commemorate gods, mark celestial bodies, reflect ancient translations—but their primary job remains undone.
We can fix this. A numbered week, Monday to Saturday as Week One through Week Six, plus Sunday—the original day of rest—preserved by tradition and common sense. Six ancient words retired, six clear replacements offered.
Our Recommendation: Week Six. The last day of the working week. The last ancient word retired. The first week of better English begins.