The comment about sacred days got me thinking about the names of the days...
"The Naming of the Days
The Greeks named the days week after the sun, the moon and the five known planets, which were in turn named after the gods Ares, Hermes, Zeus, Aphrodite, and Cronus. The Greeks called the days of the week the Theon hemerai "days of the Gods". The Romans substituted their equivalent gods for the Greek gods, Mars, Mercury, Jove (Jupiter), Venus, and Saturn. (The two pantheons are very similar.) The Germanic peoples generally substituted roughly similar gods for the Roman gods, Tiu (Twia), Woden, Thor, Freya (Fria), but did not substitute Saturn."
The Portuguese appear to be the only 'romance' language to have broken away from the ancient gods (ie Sabbath, God's day, 2nd day, 3rd day etc.)http://www.brazil-help.com/week.htm