La Morte di Caesare by Vincenzo Camucci (1798)

The Ides of March was made famous by Shakespeare in the play Julius Caesar (Act I, Scene 2), where a soothsayer warns Caesar “Beware the Ides of March”. Julius Caesar, was of course, assassinated in 44 BC on the 15th of March, a date known as the Ides of March. It’s really not so bad and ominous as days go if one understands more about the Roman calendar. The Romans didn’t count calendar days like we do. They used a reverse-count to reference days, always before and never after. Three days had names. The beginning of the month was called the Kalends, the middle called Ides, and they also had Nones, meaning 8th day before (or 9th day before and including) the Ides. The Nones occur on the 5th except by this rhyme: “March, July, October, May. The Nones are on the seventh day“. From this, it’s clear that for Nones on the 5th, Ides are on the 13th (short months), while for Nones on the 7th, Ides are on the 15th (long months). The Roman method of counting days was inclusive, so the Kalends, Nones and Ides would be counted as one of the days. For example March 3 (5 Nones) counts 3,4,5,6,7 (or 5 days) for the total. Romans would say like the following, apparently logical in Latin for them:

March 1: Kalends of March
March 2: 6 Nones of March (Ante Diem VI Nones)
March 3: 5 Nones of March
March 4: 4 Nones of March
March 5: 3 Nones of March (Ante Diem III Nones)
March 6: 2 Nones of March or Pridie Nones of March
(Pridie is Latin for “day before”)
March 7: Nones of March
March 8: 8 Ides of March (Ante Diem VIII Ides)
March 9: 7 Ides of March
March 10: 6 Ides of March
March 11: 5 Ides of March
March 12: 4 Ides of March
March 13: 3 Ides of March (Ante Diem III Ides)
March 14: 2 Ides of March or Pridie Ides (day before the Ides)
March 15: Ides of March
March 16: 17 Kalends of April (Ante Diem XVII Kalends)
March 17: 16 Kalends of April
March 30: 3 Kalends of April (Ante Diem III Kalends)
March 31: 2 Kalends of April or Pridie Kalends of April
(day before the Kalends)
April 1: Kalends of April

So, after Kalends one counts days before Nones, after Nones one counts days before Ides and after Ides one counts days before next Kalends. It’s a bit different for long and short months, but here’s a rhyme to help out:

On March the 7th, May, July,
October too, the Nones you spy;
Except in these, those Nones appear
On the 5th day of all the year.
If to the NONE you add an 8
Of every IDE you’ll find the date.

Fortunate for Shakespeare that the day Caesar was killed had such a nice ring to it that he could pen the famous line “Beware the Ides of March”, for if Caesar had been killed on the next day it would not have sounded as ominous to say “Beware the 17 Kalends of April”. Nevertheless, aside from it being the day of the death of Caesar there is nothing particularly foreboding for most of us about the Ides of March itself, and each month has an Ides as the Romans referred to them.