Fixing the calendar

Big question: Why did the Romans need to reform their calendar, and how did the reform last?

A unit from Hearth Learning, built on Innovation in History in Hearth Library. Every source page has the original beside a plain English translation, notes on who made it and how far to trust it, and page images where they exist. Sources marked “Early version” have not yet been checked by a separate review.

Lesson plan

Day 1: The year before Caesar (45 minutes)

  1. 10 minutes: Read How the Romans fixed the year by Censorinus, passages 20.2 to 20.5. Students write down the first two stages of the Roman year: ten months of 304 days, then twelve months of 355.
  2. 10 minutes: Read passages 20.6 and 20.7. Students say who was given the task of inserting the extra months and what most of them did with it.
  3. 10 minutes: Read Where the months got their names by Macrobius, passages 12.39 and 14.1. Students note what went wrong with Romulus's year and what the priests did for the tax contractors.
  4. 15 minutes: Students start a timeline of the Roman year. At each stage they write who made the change (or that no one is named), on whose authority, and the reason given.

Day 2: Caesar's reform (45 minutes)

  1. 15 minutes: Read Censorinus, passages 20.8 to 20.10. Students check his sum for 46 BCE (355 + 23 + 67 = 445) and read the note on the manuscripts' 64 days to see how an editor decides which number to print.
  2. 15 minutes: Read Macrobius, passages 14.2, 14.3, 14.6 and 14.7. Students list what Caesar did, who helped him, and where Macrobius's figure for the last year of confusion differs from Censorinus's.
  3. 15 minutes: Read Censorinus 20.9 and Macrobius 14.12. Students explain why Caesar put the new days at the ends of the months and why he made them court days. The encyclopedia article The Julian calendar gives more background.

Day 3: How the reform lasted (45 minutes)

  1. 10 minutes: Read Macrobius, passages 14.13 to 14.15. Students explain the priests' new error, how Augustus corrected it, and why he had the arrangement engraved on bronze.
  2. 10 minutes: Read Censorinus, passages 21.7, 22.16 and 22.17. Students note how Censorinus counts the Julian years in 238 CE, which two months were renamed, and what happened to the months later emperors named after themselves.
  3. 10 minutes: Groups take one word each. Impact: what the old confusion cost, and whom it helped (20.7). Influence: who kept the reform going after Caesar. Change: what Caesar changed and what he kept in place, such as the festivals and the place of the extra day.
  4. 15 minutes: Each student writes a paragraph answering both halves of the unit question, citing both writers and naming one point where they disagree.

Sources

How the Romans fixed the year

Censorinus, 238 CE. Moderate.

  1. Comprehension. According to Censorinus, who was given the task of inserting the extra months, and what did most of them do with it?
  2. Analysis. Censorinus says that most Greek cities fitted their months to the moon, and that the Romans copied them when they had a year of 355 days. Why could a calendar built on the moon not stay in step with the sun, and how did Caesar's reform deal with the problem?
  3. Analysis (reliability). Censorinus wrote in 238 CE, nearly three hundred years after Caesar's reform, in a book he gave his patron as a birthday present. The scholar Teuffel thought he took most of his learning from Suetonius, and the manuscripts give one of his numbers differently from the figure editors print. What reasons do we have to trust his figures for the reform, and what reasons to be careful?
  4. Connection. Read Where the months got their names. Macrobius makes the last year of confusion 443 days long, while Censorinus gives 445. Macrobius also tells of a later mistake by the priests, who inserted the extra day too often until Augustus corrected it; Censorinus does not mention this. When two ancient writers disagree or one leaves something out, what would you want to know about each before deciding whom to follow?

Key terms: civil year (the calendar year that a city keeps by its own rules, as opposed to the natural year); natural year (the time the sun takes to complete its course, which brings the seasons back around); full and hollow months (the longer months were called "full" and the shorter ones "hollow"; in the ten-month year they had 31 and 30 days); pontiffs (the members of Rome's most important group of priests; their head was the chief pontiff); consul (one of the two chief officials of Rome, who served for one year; a year could be named after its consuls); Olympiad (a four-year period between the games at Olympia, counted from 776 BCE); bissextum (the extra day of Caesar's calendar, inserted every fourth year by counting the sixth day before the Kalends of March twice)

Activity: Students draw a timeline of the Roman year in the stages Censorinus gives, from Romulus's ten months of 304 days, through the twelve months of 355 days and the extra month every other year, to Caesar's year of 365 days and a quarter. At each stage they write who made the change (or note that he names no one), according to which authority, and the reason Censorinus gives. They then check his sum for the year 46 BCE (355 + 23 + 67 = 445) and read the note on the manuscripts' 64 days to see how an editor decides which number to print.

Where the months got their names

Macrobius, early fifth century CE; the dialogue is set in the 380s. Moderate.

  1. Comprehension. According to Macrobius, how many months and days did the year of Romulus have, and what went wrong with it?
  2. Analysis. For April, Macrobius gives two explanations of the name and then says which one it is right to believe. For May he reports several and does not choose. What kinds of evidence do his authorities use for their explanations? Why might he decide in one case and not in the other?
  3. Analysis (reliability). Macrobius wrote around 400 CE about Romulus, Numa and Julius Caesar. He puts these words in the mouth of Praetextatus, a real senator, at a gathering that is a literary fiction, and he names the earlier scholars he used. What can this passage tell us reliably, and what can it not?
  4. Connection. Read How the Romans fixed the year. Censorinus reports that Varro took March from Mars because the Latins were warlike, not because Mars was Romulus's father, and May from the goddess Maia. Compare how Censorinus and Macrobius handle the disagreements among their authorities. Which writer tells you more clearly what he himself believes, and which approach is more useful to a historian?

Key terms: Kalends (the first day of a Roman month); Nones (the fifth or seventh day of a Roman month); Ides (a named day of each Roman month, eight days after the Nones); flamens (Roman priests, each of whom served one particular god); auspices (signs from the gods, at first read in the flight of birds, that an official watched for to learn whether the gods approved of an action); intercalary month (an extra month inserted from time to time to bring the calendar back into line with the seasons); bissextum (the extra day of Caesar's calendar, inserted every fourth year by counting the sixth day before the Kalends of March twice; it gave "bissextile," an old name for a leap year)

Activity: Groups each take two or three months and make a chart with one row for every explanation of the month's name that Macrobius gives. For each row they write who held the view (such as Fulvius Nobilior, Cingius, Varro or Cornelius Labeo, or simply "some people"), the evidence offered, and whether that evidence comes from religion, from the sound of a word, or from politics. The class then puts the charts together and discusses which kind of evidence is most common and which month names rest on the firmest ground.

Standards

Printable worksheet for any source: https://hearthinteractive.com/learning/worksheet.html

Translations drafted by Claude (Anthropic). Free to use in class. Hearth Learning, https://hearthinteractive.com/learning/