Hodie et VIII Ides di Julius

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).

Days in March

March 1: Kalends; March 2: VI Nones; March 3: V Nones; March 4: IV Nones; March 5: III Nones; March 6: Pridie Nones (Latin for "on the day before"); March 7: Nones; March 15: Ides

So, the Ides of March is just one of a dozen Ides that occur every month of the year. Kalends, the word from which calendar is derived, is another exotic-sounding term with a mundane meaning. Kalendrium means account book in Latin: Kalend, the first of the month, was in Roman times as it is now, the date on which bills are due.