The Timpson Lyceum · History of Rome – Titus Livius (2025)

Numa Pompilius, Second King of Rome– Lecture 3 (History of Rome)

Overview

Where Romulus was a warrior, his successor Numa Pompilius was a priest. This lecture covers Rome's second king — the Sabine chosen after a long, dangerous interregnum — and the religious and civic order he was credited with founding. Numa's reign is remembered as an unbroken peace: no wars, the doors of Janus shut, and the energy of a warlike people redirected into festivals, priesthoods, and a reformed calendar. If Romulus gave Rome its body, tradition says Numa gave it its soul.

The reign matters because Roman religion and Roman government were never separate spheres — priesthoods were offices of state, temples were government buildings, and the calendar itself was a religious instrument. Numa's institutions (the Vestals, the pontiffs and Pontifex Maximus, the fetiales, the temple of Janus) and his lunar calendar shaped daily Roman life for a thousand years; the title Pontifex Maximus survives to this day in the papacy.

Key Concepts

• The interregnum — After Romulus, the 200-member Senate (100 Latins, 100 Sabines) deadlocked for nearly a year, each faction refusing the other's candidate and cycling through 5-day interreges. The impasse threatened the whole state.
• The compromise — They agreed that the Latins would choose the king but the man must be a Sabine — restitution for the Sabines' murdered co-king Titus Tatius. Their choice fell on Numa.
• Numa Pompilius — A Sabine from the town of Cures, famous for wisdom and piety, who did not even live in Rome and at first refused the crown. Reluctantly accepting, he reigned in peace for a traditional 43 years.
• The Pythagoras anachronism — Legend made Numa a pupil of Pythagoras, but the philosopher lived roughly 570–490 BC while Numa's reign falls in the early 7th century BC — over a century too early. The story is chronologically impossible and reflects later Greek influence, not fact.
• "A city among cities" — Livy's judgment that Numa civilized Rome: under Romulus it had seemed a mere armed camp; Numa made it a genuine civitas, easing its neighbors' fear.
• The old calendar — Before Numa, Rome used a 10-month year of about 304 days beginning in March (Martius), followed by an unnamed, unnumbered stretch of "winter." The month names Quintilis–December ("fifth" through "tenth") preserve this older count.
• Numa's lunar calendar — Numa built a 12-month year tracking the moon (a lunation is about $29.5$ days), totaling roughly 355 days, and added the months of January and February.
• Intercalation and Mercedonius — Because the lunar year fell short of the solar year, an extra month, Mercedonius (~22–23 days), was inserted periodically to realign it. Deciding when and how long fell to the priests — the calendar was theirs to manage until Julius Caesar's reform.
• Kalends, Nones, Ides — Numa fixed the sacred waymarks of each month: the Kalends (1st), the Nones (~one-quarter in), and the Ides (~the middle). Romans dated events by nearness to these festivals and the reigning magistrates, not by numbered days.
• The Vestal Virgins — Priestesses of Vesta, goddess of the hearth, sworn to chastity and charged with keeping Rome's eternal sacred fire burning.
• Pontiffs and the Pontifex Maximus — Numa created the college of pontifices and the office of Pontifex Maximus to oversee all public religion — festivals, funerals, records, and the calendar — independent of the king's own priestly power (the rex sacrorum role). The king kept religious authority; the Pontifex Maximus handled the day-to-day.
• The temple of Janus — Its doors stood open in war and closed in peace. Shut throughout Numa's reign, they would rarely close again in Roman history — a public sign, legible to any Roman child, of whether Rome was at war.
• The fetiales and sacred days — Numa also instituted the fetiales, priests who oversaw treaties and the ritual declaration of war, and divided the calendar into sacred (nefasti) days, when work and public business were forbidden, and ordinary profane (fasti) days.

Worked Example

Why a lunar calendar drifts, and how Mercedonius corrects it. Numa's problem was that a year of moons does not match a year of seasons. Track the gap and the fix.

1. Length of the lunar civil year. Twelve lunations run $12 \times 29.5 = 354$ days; the Roman civil year was set slightly longer, about $355$ days (Romans favored odd numbers as lucky).

2. Length of the solar year — the seasons' true period:

$365.25 \text{ days}.$

1. The annual drift is the difference. Each year the lunar calendar falls behind the sun by

$365.25 - 355 = 10.25 \text{ days}.$

Left alone, spring festivals would slide into winter within a couple of decades.

1. Accumulate the drift over four years:

$4 \times 10.25 = 41 \text{ days}.$

1. Correct with the intercalary month. Inserting Mercedonius twice in that span — say $23$ days once and $22$ days once — adds

$23 + 22 = 45 \text{ days},$

which slightly overshoots the $41$-day deficit, so over a four-year cycle the calendar swings a few days ahead and back rather than running away. The Roman scheme did exactly this, alternating intercalations across a multi-year period.

1. Compare the precision. Numa's patch left a residual wobble of a few days each cycle; Caesar's later solar reform fixed the year at $365.25$ days with a single leap day every four years, giving an average error of only

$365.25 - 365.2422 \approx 0.0078 \text{ days/year},$

more than a thousandfold tighter — which is why the priest-managed intercalation, open to error and manipulation, eventually had to go. $\blacksquare$

Summary

• After a near-year of deadlocked interregnum, Rome's factions agreed the Latins would elect but the king must be a Sabine — the wise and pious Numa Pompilius of Cures.
• Numa's reign was one of total peace; the story making him a student of Pythagoras is a chronological impossibility of over a century.
• He reformed the calendar from a 10-month, ~304-day year to a 12-month, ~355-day lunar year, adding January and February and correcting the ~10.25-day annual drift with the intercalary month Mercedonius.
• He founded core religious institutions — the Vestal Virgins, the pontiffs and Pontifex Maximus, the fetiales, and the temple of Janus — embedding religion permanently in Roman government.
• Roman religion and state were inseparable: priests kept the records, temples housed public business, and time itself was measured by Kalends, Nones, and Ides and by sacred versus profane days.