Egyptian Days (dies Aegyptiaci) refer to 24 days of the year that signify bad luck or ill omen.
The Egyptian Days are the following: January 1 and 25, February 4 and 26, March 1 and 28, April 10 and 20, May 3 and 25, June 10 and 16, July 13 and 22, August 1 and 30, September 3 and 21, October 3 and 22, November 5 and 28, and December 7 and 22.
The above days were considered inauspicious for any new ventures. In olden days, doctors restrained themselves from performing surgeries and major treatments on these days. Different days have different degrees of bad luck. Some of them were partly good and partly evil, while others were considered totally disastrous.
There are arguments about the exact dates of the Egyptian Days. Hesoid, a Greek poet, mentioned some of these days in his poetry. He recommended the eleventh day of every month as the most auspicious day for reaping while the fifth and the thirteenth were considered the most ominous.
Behind the concept of Egyptian days lies the wider discipline of astrology. Ancient scholars believed that the position of the planets and hence the dates have a great influence on human lives. There was a reference in Marco Polo's travel experience about a Persian Brahmin who measured the length of his shadow before making a purchase. The length of the shadow signified the destiny of the day.
Egyptian Days are not followed only in Egypt. The dates may vary in different countries, but the belief has the common base, that is, astrology.