In long ago times, Re, the chief god, still reigned the earth as a living Pharaoh. He lived in a huge palace on the banks of the River Nile, and all the people of Egypt came to bow down before him. All his courtiers did exactly what he asked, and he spent his time hunting, playing games and feasting. It was a wonderful life.

However, one day a courtier came to him about a conversation that he had overheard. Troth, god of all wisdom and magic, had told the goddess Nut that one day her son would be pharaoh of Egypt.

Re was furious. No one else was worthy of being Pharaoh. He paced back and forth, shouting, "how dare they do such a thing! No child of Nut will dethrone me!" He thought for a long time. Eventually, summoning his magic powers he said, "I lay this curse: No child of Nut will be born on any day or night of any year," News travelled fast among the gods, so Nut soon heard the curse. She was heartbroken. She wanted a child, but she knew that Re's magic was very strong. How could she break the curse? The only person who might be able to help was Troth, the wisest of all gods, so she set off to see him at once. Troth loved Nut and, when he saw her tears, he decided to help her. "I cannot lift Re's curse," he said, "but I may be able to get around it. Just wait."

Troth knew that Khonsu, the moon-god, was a gambler, so he challenged him to a game of senet. Khonsu did not stop to think for a moment. He could not resist a challenge.

"O, Thoth," he said. "You may be the wisest god, but I am the greatest senet player ever. I have never lost a game. I will play you and I will win every game!"

The two set down to play. From the start, Thoth won every game. "You have just been lucky, Thoth," said Khonsu. "I bet an hour of my light that I will win the next game." But he still lost! Thoth kept on winning and Khonsu kept on betting his own light until Thoth had won enough of Khonsu's light to equal five whole days. Thoth stood up, thanked Khonsu and left, taking Khonsu's light with him.

"What a coward," muttered Khonsu to himself. "My luck was just changing. I would have won the next game!"

Thoth fitted the five extra days in between the end of that year and the beginning of the next. At the time, a year was made up of twelve months, each with 30 days, making a total of 360 days in the year.

Nut was overjoyed when Thoth told her what he had done, because the five extra days were not days in the year, Nut's children could be born on these days without breaking Re's curse.

On the first day, Nut gave birth to Osiris, who was to be Pharaoh after Re; on the second day to Harmachuis, who is immortalised as the Sphinx; on the third day to Set, who later killed Osiris and became Pharaoh; on the forth day to Isis, who became Osiris's wife, and on the fifth day to Nephthys, who was to be Set's wife.

As for Khonsu the moon-god, he was so weak after the game that he lost a lot of strength forever. He could no longer shine brightly all the time. Even today, the moon only shines brightly on a few days of the month and has to spend the rest of the time gathering its strength together.

http://www.newman.ac.uk/~s.l.edwards/nuts.html