Measures, Money & the Roman Calendar: Latin Grammar

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GrammarMeasures, Money & the Roman Calendar

Measures, Money & the Roman Calendar

A&G §630–638|10 rules|0 practice questions

When you read Cicero's letters or Caesar's dispatches, the numbers feel alien on purpose. Romans counted money in asses and sēstertiī, marched in passūs, weighed grain in librae, and — most famously — dated their letters by counting backwards from three fixed points each month: the Kalendae (1st), Nōnae (5th or 7th), and Īdūs (13th or 15th).

This hub is the reference shelf for all of it. Ante diem III Kalendās Mārtiās doesn't mean "on March 3rd" — it means "the third day before March 1st," which (because Romans counted inclusively) lands on February 27. That single counting habit trips up everyone the first time.

Pattern

ante diem N + [Kal. / Nōn. / Īd.] + (month, acc. pl.)

Roman Date Formula

"on the Nth day before the Kalends/Nones/Ides of [Month]" — count INCLUSIVELY back from the next fixed point.

ante diem III Kal. Mārt. = Feb 27 (count: Mar 1, Feb 28, Feb 27 = 3 days). prīdiē replaces ante diem II.

The Roman Yardstick: Money, Length, Weight, Capacity, Time

as — the copper unit, 12 unciae

1 as ≈ a pound of copper (originally)

critical

sēstertius (HS) — silver, the unit of value

1 HS = 4 asses (later); nummus often = HS

critical

dēnārius — silver, soldier's daily wage

1 dēnārius = 4 sēstertiī = 16 asses

critical

aureus — gold, large transactions

1 aureus = 100 sēstertiī

common

sēstertium — sum of money (neuter noun)

tria sēstertia = 3,000 HS; deciēns HS = 1,000,000 HS

important

pēs — Roman foot (~11.65 English in.)

12 unciae = 1 pēs

important

passus — pace, 5 feet

1 passus = stride from heel to heel

common

mīlle passuum — Roman mile (4,850 ft)

mīlia passuum octō = "8 miles" (B. G. i. 21)

critical

iūgerum — land area (≈ ⅔ acre)

240 × 120 Roman feet

common

libra — pound (~¾ lb avoirdupois)

12 unciae = 1 libra; sēmis = ½ libra

important

talentum — Greek weight, 60 librae

Used in eastern campaigns and Greek contexts

common

modius — dry capacity (peck)

16 sextāriī = 1 modius; grain ration unit

important

amphora — liquid capacity (6 gallons)

8 congiī = 1 amphora; standard wine jar

common

Kalendae / Nōnae / Īdūs — month's three fixed points

Kalendīs Iānuāriīs = Jan. 1; Īdibus Mārtiīs = Mar. 15

critical

ante diem N Kal./Nōn./Īd. — backward dating

a.d. VI Kal. Nov. = Oct. 27 (Sall. Cat. 30.1)

critical

ab urbe conditā — year reckoned from 753 B.C.

A.U.C. 691 = B.C. 63 (subtract from 754)

important

See It In Action

Kalendis Iānuāriis L. Cottam et L. Torquātum cōnsulēs interficere

on January 1st, they were planning to kill the consuls L. Cotta and L. Torquatus

— Sall. Cat. 18.5

Notice Kalendīs Iānuāriīs — bare ablative for "on the Kalends of January." The fixed points (Kal., Nōn., Īd.) take ablative without a preposition; the month is an adjective agreeing with them.

C. Manlium arma cēpisse ante diem VI Kalendās Novembrīs

(it was written) that C. Manlius had taken up arms on October 27th

— Sall. Cat. 30.1

The arithmetic: November has 30 days, so Kal. Nov. = Nov. 1; counting back 6 inclusively (Nov. 1, Oct. 31, 30, 29, 28, 27) lands on Oct. 27. ante diem + accusative is frozen idiom — don't try to parse it like normal Latin.

hostēs sub monte cōnsēdisse mīlia passuum ab ipsīus castrīs octō

(he learned) that the enemy had settled below the mountain eight miles from his camp

— B. G. i. 21

mīlia passuum octō is how Romans say "eight miles" — literally "eight thousands of paces." passuum is a partitive genitive locked into the idiom; the number agrees with mīlia.

HS LX, quod advexerat Domitius atque in pūblicō dēposuerat, Domitiō reddit

He returns 60,000 sesterces, which Domitius had brought and deposited in the treasury, to Domitius

— B. C. i. 23

HS LX with a line over LX = 60,000 sesterces, not 60. The horizontal stroke (we render it inline) is Roman shorthand for "× 1,000." Caesar uses this in financial reports throughout the Civil War.

Reading Roman Dates and Sums in English

Date on a fixed point

[Kal./Nōn./Īd.] [Month adj., abl.] → "on [the date]"

Kalendīs Iānuāriīs → "on January 1st"

Date counted backward

ante diem N [Kal./Nōn./Īd.] [Month, acc.] → use the formula, then convert

a.d. III Kal. Mārt. → Feb 27 (31+2−... wait: Feb has 28, so 28+2−3 wouldn't apply; rule is days-in-prev-month + 2 − N for Kal., so 28+2−3 = Feb 27)

Day before a fixed point

prīdiē [Kal./Nōn./Īd.] [Month, acc.] → "the day before [date]"

prīdiē Kalendās Iānuāriās → December 31

Year as A.U.C.

annō urbis conditae N → year B.C. = 754 − N (for years before A.D.)

A.U.C. 691 → B.C. 63 (Cicero's consulship)

Sum with sēstertium

deciēns sēstertium → numeral adverb × 100,000 sesterces

deciēns HS → 10 × 100,000 = 1,000,000 sesterces

Inclusive Counting vs. Exclusive Counting

Roman dates count INCLUSIVELY — both endpoints are in the total. English counts exclusively. This is why ante diem III is two days before, not three.

Roman (inclusive)

count both endpoints

ante diem III Kal. Mārt.

Mar 1, Feb 28, Feb 27 = 3 days → Feb 27

English (exclusive)

count only days between

"3 days before March 1"

Feb 26 (Feb 27, 28, 29 between)

Tip: Quick formula: for ante diem N Kal., day = (days in previous month) + 2 − N. So a.d. VIII Kal. Feb. = 31 + 2 − 8 = Jan. 25.

Quick Check

A Cicero letter is dated ante diem IV Kalendās Iānuāriās. Counting inclusively from the Kalends of January (Jan. 1), what date is this?

Study Tips

•Memorize the three fixed points (Kalendae 1st, Nōnae 5th/7th, Īdūs 13th/15th) and the rhyme "in March, July, October, May, the Nones fall on the 7th day" — the rest is arithmetic.
•When you hit ante diem III Kal. Mārt., do the count: 1 (March 1) + 1 (Feb 28) + 1 (Feb 27) = the 3rd day back, inclusive, lands on Feb 27. Practice on three real Cicero letter dates.
•For money, anchor on sēstertius (HS) as the unit — dēnārius = 4 HS, aureus = 100 HS. Big sums use sēstertium (the noun, not the coin) with numeral adverbs: deciēns HS = 1 million sesterces.
•Mīlle passuum literally is "a thousand of paces" — the partitive genitive is the giveaway. The Roman mile is shorter than ours (4,850 ft, not 5,280).

See It In Action

Kalendis Iānuāriis L. Cottam et L. Torquātum cōnsulēs interficere

on January 1st, they were planning to kill the consuls L. Cotta and L. Torquatus

— Sall. Cat. 18.5

C. Manlium arma cēpisse ante diem VI Kalendās Novembrīs

(it was written) that C. Manlius had taken up arms on October 27th

— Sall. Cat. 30.1

hostēs sub monte cōnsēdisse mīlia passuum ab ipsīus castrīs octō

(he learned) that the enemy had settled below the mountain eight miles from his camp

— B. G. i. 21

mīlia passuum octō is how Romans say "eight miles" — literally "eight thousands of paces." passuum is a partitive genitive locked into the idiom; the number agrees with mīlia.

HS LX, quod advexerat Domitius atque in pūblicō dēposuerat, Domitiō reddit

He returns 60,000 sesterces, which Domitius had brought and deposited in the treasury, to Domitius

— B. C. i. 23

HS LX with a line over LX = 60,000 sesterces, not 60. The horizontal stroke (we render it inline) is Roman shorthand for "× 1,000." Caesar uses this in financial reports throughout the Civil War.

Study Tips

•Memorize the three fixed points (Kalendae 1st, Nōnae 5th/7th, Īdūs 13th/15th) and the rhyme "in March, July, October, May, the Nones fall on the 7th day" — the rest is arithmetic.

•When you hit ante diem III Kal. Mārt., do the count: 1 (March 1) + 1 (Feb 28) + 1 (Feb 27) = the 3rd day back, inclusive, lands on Feb 27. Practice on three real Cicero letter dates.

•For money, anchor on sēstertius (HS) as the unit — dēnārius = 4 HS, aureus = 100 HS. Big sums use sēstertium (the noun, not the coin) with numeral adverbs: deciēns HS = 1 million sesterces.

•Mīlle passuum literally is "a thousand of paces" — the partitive genitive is the giveaway. The Roman mile is shorter than ours (4,850 ft, not 5,280).