These were called by the Greeks " decans," because ten degrees of the ecliptic and ten days of the year were presided over by each.
The college of the decans was conceived as moving, by their annual risings and settings, in an " eternal circuit " between the infernal and supernal regions.
In Egypt celestial influences were considered'as emanating mainly from the thirty-six " decans " of the signs.
12 As early as the 14th century B.C. a complete list of the decans was placed among the hieroglyphs adorning the tomb of Seti I.; they figured again in the temple of Rameses II., 13 and characterize every Egyptian astrological monument.
The decans are ranged on the outermost of its five concentric zones; the planets and the Greek zodiac in duplicate occupy the next three; while the inner circle is unaccountably reserved for the Chinese cyclical animals.