Surviving calendars from ancient Egypt categorize each day of the year as either lucky or unlucky (Reminds me of that goofy country song- the stars are stacked against you dear, get back in bed!). Days were apparently categorized based on mythical events that supposedly happened on them eons ago. For example, a day when one of the gods had made a successful journey= good. A day when two of the gods fought= bad. Possibly very, very bad.
This meant than any Egyptian planning a major event or even performing certain rituals would know whether the day they chose was auspicious. Temples consulted these luck calendars and individuals also possessed them- some of them have been found in various tombs.
Kind of sounds like the Farmer's Almanac, doesn't it? I always wonder about this kind of stuff. Was it the whole population that was obsessed with lucky and unlucky days or just a select few?
The Egyptian calendar was a 360 day calendar with an extra five days added on. They didn't have leap year so after several centuries the calendar got all wacky. According to the mythology, those five days were added on so that Osiris, Isis, Seth, Nepthys, and Horus the Elder could be born. They were considered extremely unlucky- nothing of consequence was ever to be done on those days.
These luck calendars were also used to predict a child's future depending on what day they were born on. If a child was born on the fifth day of the second month of Akhet, it was predicted that their death would be caused by copulation. Quite a way to go, eh?
Believe it or not, these Egyptian lucky and unlucky days made it all the way through to Medieval times- the observance of such days were one of the charges made against heretics in France all the way to the 13th century. Ohdalolly!