Editing Calends (section)

== Use ==
The [[Ancient Rome|Romans]] called the first day of every month the ''calends'', signifying the start of a new [[lunar phase]]. On this day, the [[pontiff]]s would announce the number of days until the next month at the [[Curia Calabra]]; in addition, debtors had to pay off their debts on this day. These debts were inscribed in the ''kalendaria'', effectively an accounting book. 

Modern calendars count the number of days ''after'' the first of each month; by contrast, the Roman calendar counted the number of days ''until'' certain upcoming dates (such as the calends, the [[nones (calendar)|nones]] or the [[ides (calendar)|ides]]). The day before the calends was called ''pridie kalendas'', but the day before that was counted as the "third day", as Romans used [[inclusive counting]]. 

To calculate the day of the calends of the upcoming month, counting the number of days remaining in the current month is necessary, then adding two to that number. For example, April 22 is the 10th day before the calends of May (ante diem decimum Kalendas Maias/Maii), because eight days are left in April and both end dates are included in the total.<ref>[https://search.library.wisc.edu/digital/A4C5AV6Q7LZ5DY8E/full/AGINLPYZBRQPMF8K "Calends"], [[Cyclopaedia, or an Universal Dictionary of Arts and Sciences|Chambers' Cyclopaedia]] (1728), Vol. 1, p. 143</ref>