What Are the Ides of March, Anyway?

Last night my friend's son asked us what the Ides of March were, and I was stumped. "It's something to do with Shakespeare" was the best I could come up with, along with "It's what you say every year on March 15th!" So this is for Scott.

From about.com's Astrology section:

Julius Caesar was assassinated on March 15, 44 B.C.E. []

The warning itself was made famous in Shakespeare's play on Julius Caesar, when an unidentified soothsayer tells Caesar, who is on his way to the Senate (and his death), "Beware the ides of March." Caesar replies, "He is a dreamer; let us leave him. Pass."

Caesar ignored the warning, went to the Roman Senate, and was killed.

What's an ide?

The term Ides comes from the earliest Roman calendar, which is said to have been devised by Romulus, the mythical founder of Rome. Whether it was Romulus or not, the inventor of this calendar had a penchant for complexity. The Roman calendar organized its months around three days, each of which served as a reference point for counting the other days:

* Kalends (1st day of the month)
* Nones (the 7th day in March, May, July, and October; the 5th in the other months)
* Ides (the 15th day in March, May, July, and October; the 13th in the other months)

The remaining, unnamed days of the month were identified by counting backwards from the Kalends, Nones, or the Ides. For example, March 3 would be V Nones—5 days before the Nones (the Roman method of counting days was inclusive; in other words, the Nones would be counted as one of the 5 days).

And from wikipedia, this compendium of alternate uses of the phrase "Ides of March":

Ides of March is also a novel by Thornton Wilder, describing, in a series of documents, the events leading up to the death of Julius Caesar.

"The Ides of March" is also an instrumental song by Iron Maiden from their 1981 album, Killers.

The Ides of March is also a band who performed the 1970 hit, "Vehicle."

"Ides of March" is the name of the season 4 finale of the television series Xena: Warrior Princess. The events of the episode roughly correlate with the key elements in the Shakespeare play, with Xena warning Brutus to beware the Ides of March, implying Caesar had become uncontrollably megalomaniacal.

And March 15th is also home to these holidays and observances (also from wikipedia):

# Turkey buzzards return to Hinckley, Ohio.
# International Day Against Police Brutality
# For corporations in the United States that use the calendar year as their fiscal year, the date on which the corporation must file its corporate income tax return
# National holiday in Hungary celebrating the 1848 Revolution.
# World Consumer Rights Day

Happy birthday to Ruth Bader Ginsburg, Jimmy Swaggart (there's a match made in astrological heaven), Sly Stone, Ry Cooder, and Harold Baines.