Nut (goddess)
The ancient Egyptians had three calendars, but the Agricultural one was the one that was used in everyday life. It was made up of three seasons, each containing four months. The seasons were Akhet, (the inundation) Peret (when the water retreated) and Shemu (harvest season). Nut loved Geb, but Ra was not happy that she loved Geb so he told Shu, their father (the air god) to separate them. Then, Ra put a curse on Nut so she could not have babies on any of the three-hundred sixty days of the year. Thoth wanted to let Nut be able to have babies so he challenged Khonsu, the moon god, to a game of Senet. If he won, he would be able to add five days to the year. If he lost, he would be killed. Thoth won and added five more days to the year. On the first day, Nut had Osiris to replace Ra, but Set later deceived him and Osiris became god of the underworld. On the second day she had Horus, the war god. On the third day, she had Set, the god of storms, evil, and Chaos, on the forth day she had Isis the goddess of magic, and on the fifth day she had Nephthys the river goddess. After a long time, the Egyptians realized the calendar was off because they did not have the quarter day at the end, like we do by having leap years. The calendar said it was flood season, but the flood did not come until later. The ancient Egyptians noticed the star Sirius would rise right before the flood. They used this as the beginning of the year and as the beginning of flooding.