Calends

Calends, or Kalends (from a word meaning to call), the first day of the Roman month on which the feast days and unlucky days, on which no business might be done, were publicly proclaimed. The dates in the latter part of the Roman month are reckoned backwards, counting inclusively from the calends of the next month: thus, September 20 is "the twelfth day before the calends of October." The "ides" (so-called because they divide the month) are on the 13th or 15th, according to the month, the "nones" on the 5th or 7th, i.e. nine days before the ides, counting inclusively. Dates between the calends and nones are counted backwards from the nones, between the nones and ides backwards from the ides. As the Greek calendar has no calends, "to pay at the Greek calends" (said by Suetonius to have been a favourite colloquial phrase of the Emperor Augustus) meant not to pay at all.