Origin of the Weeks and Calendar

The origin of the seven-day week is one of the great mysteries in the human history. Many of us don't know which process had determined this seven-day week that rules our life and activities. The English names of the seven days derived from the Saxon. The ancient Saxons had borrowed the week from some Eastern nation, and substituted the names of their own divinities for those of the gods of Greece... This book deals with the origin of the seven-day weeks, and the history of the Calendar and astrology.
"The word "calendar" is derived from calendium, denoting the commencements of months, which, in the language of ancient Rome, were called dies calendæ, or simply calendæ..."