Hesiod. Works and Days. (Lines 770-779).
To begin with, the first, the fourth, and the seventh -- on which Leto bare Apollo with the blade of gold -- each is a holy day. The eighth and the ninth, two days at least of the waxing month (*H41), are specially good for the works of man. Also the eleventh and twelfth are both excellent, alike for shearing sheep and for reaping the kindly fruits; but the twelfth is much better than the eleventh, for on it the airy-swinging spider spins its web in full day, and then the Wise One (*H42), gathers her pile. On that day woman should set up her loom and get forward with her work.