The well-known superstition about sitting down thirteen to dinner, on the ground that one of the party may die shortly afterwards, is an instance of the same belief, being of course based on the Last Supper.

But the number thirteen is generally unlucky, being held to be so by the Hindus, Muhammadans and Persians, as well as Europeans, and the superstition perhaps arose from its being the number of the intercalary month in the soli-lunar calendar, which is present one year and absent the next year.

Thirteen is one more than twelve, the auspicious number of the months of the year.

Similarly seven was perhaps lucky or sacred as being the number of the planets which gave their names to the days of the week, and three because it represented the sun, moon and earth.

When a gambler stakes his money on a number such as the date of his birth or marriage, he acts on the supposition that a number which has been propitious to him once will be so again, and this appears to be a survival of the belief in the recurrence of events.
63.