Legend has it that in 46 AD, when the Roman emperor Caesar revised the calendar, it was stipulated that every year was twelve months, and the first month, March, May, July, October and December were big months, with thirty-one days each month; Other months are designated as abortion, 30 days per month. This size is half a year, which is easy to remember and easy to apply for. However, according to this regulation, a year is not 365 days, but 366 days, so it is necessary to find a month to deduct one day. Which month is suitable for deduction? At that time, all prisoners sentenced to death were executed in February, so people hoped that February would pass quickly. So February was deducted for one day. So, there are only 29 days left in February. Later, a man named Auguste became the emperor of Rome. He found that Caesar was born in July, which is a big month, and he was born in August, which is a small month. In order to show that he has the same dignity as the previous emperor, he arrogantly designated August as the big month and changed it to 3 1 day. The extra day in August was deducted from February, so there are only 28 days left in February. Only every four years, that is, leap years, February is 29 days. This is the origin of the days in February.