月の名前：September が7月ではないわけ

Here's a puzzle. "Sept" means seven, "oct" means eight, "nov" means nine and "dec" means ten. You can see them in words like "octopus", which has eight arms, and "decade", which is ten years. So why is September the ninth month, October the tenth, November the eleventh and December the twelfth? The answer is that the earliest Roman calendar started the year in March, not January. Counting from March, September really was the seventh month and December was the tenth. Later, January and February were added at the start of the year, which pushed all the other months two places along. But nobody bothered to change their names. Several of the other months are named after Roman gods and goddesses. January comes from Janus, the god of doors and beginnings, who had two faces so he could look back at the old year and forward to the new one. March is named after Mars, the god of war. That was the time of year when the weather improved and armies set off on campaigns. May probably comes from Maia, a goddess of growth, and June from Juno, the queen of the gods. February comes from a Roman festival of purification called Februa. The origin of April is uncertain, though one popular theory links it to a Latin word meaning "to open", like flowers in spring. Two months are named after real people. July was named after Julius Caesar, who reformed the calendar, and August after the first Roman emperor, Augustus. So the calendar on your wall is really a 2,000-year-old Roman history lesson.