Numbers, Their Occult Power and Mystic Virtues, by W. Wynn Westcott, [1911], at sacred-texts.com
THIRTEEN. 13.
Thirteen was the sacred number of the Mexicans and people of Yucatan: twelve of many tribes of North American Indians, as of so many nations of antiquity: this had an astronomical connection, because the Stars and Sun were Gods to them. The method of computation among the Mexican Priests was by weeks of 13 days; consult Dunlop's "Vestiges." Their year contained 28 weeks of 13 days and 1 day over, just as ours contains 52 of 7 days and one day over. Thirteen years formed an Indiction, a week of years, the 13 days over forming another week. Four times 13, or 52, years was their cycle. In Yucatan there were 13 "Snake Gods" (see Steven's "Yucatan," and Gama's "Ancient Mexicans ").
13 is the number of the Hebrew word AHBH, Ahebah, love, and of Achad, AChD, unity. Old authors state that 13 is a number used to procure agreement among married people. Hebrew ancient lore did not reckon the number 13 as unlucky; this idea arose from the fate of Judas after the Last Supper of Jesus, yet not for some centuries, but since the notion was started it has been prevalent among all Christians.
The 13 cards of each suit of a pack of Cards are sometimes applied to the 13 lunar months for purposes of divination.
The Gnostic gems are often inscribed with a 13-lettered Name for God, ABLANA Th ANALBA.
Rabbi Eliezer on account of a serious drought proclaimed 13 fasts, at the end of which rain fell at once.
The Temple used 13 collecting horns; and in it were 13 tables, and 13 devotional reverential bows were used in the full service.
When a Hebrew boy reached the age of 13 years he began to fast for the full time: a girl began at twelve years.
The word Covenant is written 13 times in the chapter on Circumcision.
The Bava Metzia gives 13 reasons for a good breakfast. In the Hebrew Liturgy are found the 13 logical rules for interpreting the law. Hershon, "Talmud Miscellany," p. 167.