[PLUG] Ides of March

[Russell Senior]

Maybe you all knew this already, but I didn't. Ides derives from (at least)
a Roman lunar calendar. Months started on the day of the first sighting of
a crescent moon, the Kalends. then the Nones was first quarter, and Ides
was the day of the full moon.

See:

  https://en.wikipedia.org/wiki/Roman_calendar#Days

Thus, March 15 is the Ides of March, because March (as defined) started on
a crescent moon and the 15th was when the moon was full. So, if March 15th
in our modern solar calendar is not a full moon, you probably don't need to
beware so much.

This was all based on 20 minutes of research, so take it for what it's
worth.