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The Julian Calendar

"First he reorganized the Calendar, which the Pontiffs had allowed to fall into such disorder, by intercalating days or months as it suited them, that the harvest and vintage festivals no longer corresponded with the appropriate seasons. He linked the year to the course of the sun by lengthening it from 355 days to 365, abolishing the short extra month intercalated after every second February, and adding an entire day every fourth year."

Suetonius, Julius Caesar (XL)

Even after the days of the month had lost any fixed correspondence with the phases of the moon, the Romans continued to count them in relation to one of three fixed points in the lunar cycle. The Kalends (from calare, "proclaim") was the first day of the month and sacred to Juno, to whom sacrifice was made at the first appearance of the crescent new moon (several days after conjunction, when it passes between the sun and the earth). It was then that the pontiff declared the number of days before the Nones, when the people again were summoned to hear the announcement of that month's festivals. The Nones (from nonus, "ninth") coincided with the first quarter of the moon and was the ninth day (counting inclusively) before the Ides (from iduare "to divide"), which occurred at the full moon and came in the middle of the month.

The Republican calendar had four long months of thirty-one days (March, May, July, October); the other months all were short, with twenty-nine days (except for February, which had twenty-eight). The Ides divided months of twenty-nine days on the thirteenth, and those of thirty-one days on the fifteenth. Because of the difficulty in determining the days of the month during the the new moon, there were, with one exception, no festivals before the Nones; rather, the majority took place after the Ides, when the full moon had begun to wane.

The Nones was on the fifth day of the month (nine inclusive days before the thirteenth), except for March, May, July, and October, when the Nones was on the seventh (nine inclusive days before the fifteenth). The Ides, then, split the month on the thirteenth (except for four long months of March, May, July, and October, when it was on the fifteenth) and was preceded by the Nones on the fifth (except for the long months, when it was on the seventh).

Counted inclusively, days were reckoned backwards from these three points, by when they occurred before the Kalends, Nones, or Ides. They were not enumerated after the Kalends but counted as so many before the following Nones; days after the Nones were numbered as being before the Ides, and those after as so many before the next Kalends. Seemingly inconvenient, counting days backwards actually is the same as saying that there are so many days until the new moon, the first quarter, and the full moon.

The Republican calendar had 355 days (the four long months of thirty-one days, the seven short months of twenty-nine, and the twenty-eight days of February). In the Julian calendar, the long months and February remained unchanged, and ten extra days were added to the short months, one or two days at the end of each to create months of thirty or thirty-one days. Although the position of the Nones and Ides remained the same, festivals and birthdays after the Ides, when the Romans counted down to the Kalends of the next month, were affected in the months whose length had changed. Festivals, therefore, either had to be recognized as occurring on the same date or the same day. Tradition was too strong for the date to change and festivals were left on the same day, that is, the same number of days after the Ides, even though their notational "date" had changed relative to the following Kalends. An example is the birth of Augustus. Suetonius records that he was born on "on the ninth day before the Kalends of October in the consulship of Marcus Tullius Cicero and Gaius Antonius" (Life, V). This was in the year 63 BC, when September had twenty-nine days and the Republican equivalent was the eighth day before the Kalends of October. With Caesar's reform, one more day was added to the month, which meant that there was one more day before the Kalends. The birthday still was on the same day (the same number of days after the Ides) but on a different date (nine days, not eight, before the Kalends).

In the Julian calendar below, the letters "a.d." abbreviate ante diem ("the day before"). Pridie is the last day of the month.


January | February | March | April | May | June | July | August | September | October | November | December


JANUARY (Mensis Januarius)

Named after Janus, the god of beginnings, and derived from ianua, "door," January began with the first crescent moon after the winter solstice, marking the natural beginning of the year. It was a time of relative ease for the farmer, with the respite from the labors of the field that began in December and continued into January. In 37 BC, Varro divided the agricultural year into eight parts (Res Rusticae, I.28.2). From the winter solstice to the beginning of the west wind, a period of forty-five days, no hard work was to be done outdoors. The farmer was expected to drain the land if wet and harrow if dry, and to prune the vineyards and orchards. Columella (De Re Rustica, circa AD 65) also advises against working the soil until the Ides, except that on January 1 the farmer may want at least to begin his tasks to ensure good luck.

1. Kalendae Januariae
2. a.d.IV.Non.Jan
3. a.d.III.Non.Jan.
4. pridie Non.Jan.
5. Nonae Januariae
6. a.d.VIII.Id.Jan.
7. a.d.VII. Id.Jan.
8. a.d.VI. Id.Jan.
9. a.d.V. Id.Jan.
10. a.d.IV. Id.Jan.
11. a.d.III. Id.Jan.
12. pridie Id.Jan.
13. Idus Januariae
14. a.d.XIX.Kal.Feb.
15. a.d.XVIII.Kal.Feb.
16. a.d.XVII.Kal.Feb.
17. a.d.XVI.Kal.Feb.
18. a.d.XV.Kal.Feb.
19. a.d.XIV.Kal.Feb.
20. a.d.XIII.Kal.Feb.
21. a.d.XII.Kal.Feb.
22. a.d.XI.Kal.Feb.
23. a.d.X.Kal.Feb.
24. a.d.IX.Kal.Feb.
25. a.d.VIII.Kal.Feb.
26. a.d.VII.Kal.Feb.
27. a.d.VI.Kal.Feb.
28. a.d.V.Kal.Feb.
29. a.d.IV.Kal.Feb.
30. a.d.III.Kal.Feb.
31. pridie Kal.Feb.

FEBRUARY (Mensis Februarius)

Originally, the last month of the year and the shortest, February derives from februa, the instruments of purification that were used to propitiate the gods of the underworld (Varro, De Lingua Latina, VI.34) and prepare for spring, which Varro indicates began on February 7. Not only did the fields, groves, and vineyards need tending, but there were duties to the spirits of dead ancestors (manera), as well as to the gods, on which the fertility of the fields depended. Expiatory rituals sought to atone for any unwitting offense given the gods, whether by commission or omission, (willful offense could not be absolved; the offender was impius.)

1. Kalendae Februariae
2. a.d.IV.Non.Feb.
3. a.d.III.Non.Feb.
4. pridie Non. Feb.
5. Nonae Februariae
6. a.d.VIII.Id.Feb.
7. a.d.VII.Id.Feb.
8. a.d.VI.Id.Feb
9. a.d.V.Id.Feb.
10. a.d.IV.Id.Feb.
11. a.d.III.Id.Feb.
12. pridie Id. Feb.
13. Idus Februariae
14. a.d.XVI.Kal.Mar.
15. a.d.XV.Kal.Mar. Lupercalia
16. a.d.XIV.Kal.Mar.
17. a.d.XIII.Kal.Mar.
18. a.d.XII.Kal.Mar.
19. a.d.XI.Kal.Mar.
20. a.d.X.Kal.Mar.
21. a.d.IX.Kal.Mar.
22. a.d.VIII.Kal.Mar.
23. a.d.VII.Kal.Mar. Terminalia
24. a.d.VI.Kal.Mar.
25. a.d.V.Kal.Mar.
26. a.d.IV.Kal.Mar.
27. a.d.III.Kal.Mar.
28. pridie Kal.Mar.

MARCH (Mensis Martius)

Named by Romulus after Mars, the god of war and protector of crops and the field, March originally was the first month of the Roman year (Ovid, Fasti, I.39). A time of renewal after the dormacy of winter, it also inaugurated the beginning of the military campaign season. On the first day of the month, the sacred fire in the Temple of Vesta was tended and fresh laurel wreaths placed in the Regia. The Kalends of every month was sacred to Juno, especially the first day of March, when wives were given presents by their husbands in an unofficial celebration called the Matronalia.

1. Kalendae Martiae
2. a.d.VI.Non.Mar.
3. a.d.V.Non.Mar.
4. a.d.IV.Non.Mar.
5. a.d.III.Non.Mar.
6. pridie Non.Mar.
7. Nonae Martiae
8. a.d.VIII.Id.Mar.
9. a.d.VII.Id.Mar.
10. a.d.VI.Id.Mar.
11. a.d.V.Id.Mar.
12. a.d.IV.Id.Mar.
13. a.d.III.Id.Mar.
14. pridie Id.Mar.
15. Idus Martiae Ides of March
16. a.d.XVII.Kal.Apr.
17. a.d.XVI.Kal.Apr.
18. a.d.XV.Kal.Apr.
19. a.d.XIV.Kal.Apr.
20. a.d.XIII.Kal.Apr.
21. a.d.XII.Kal.Apr.
22. a.d.XI.Kal.Apr.
23. a.d.X.Kal.Apr.
24. a.d.IX.Kal.Apr.
25. a.d.VIII.Kal.Apr.
26. a.d.VII.Kal.Apr.
27. a.d.VI.Kal.Apr.
28. a.d.V.Kal.Apr.
29. a.d.IV.Kal.Apr.
30. a.d.III.Kal.Apr.
31. pridie Kal.Apr.

APRIL (Mensis Aprilis)

The Romans were uncertain about the etymology of the word. Ovid associates April with Aphrodite (Venus) and, indeed, just as March was dedicated to Mars, so April, says Macrobius, was named after Venus, the parents of Rome. April also was thought to derive from aperire (to open), since this was the month that fruits and flowers blossomed. It was a time for several agricultural festivals, including the Cerialia, Vinalia, and Robigalia, which was in honor of the spirit of blight, rust, and mildew. The Floralia celebrated Flora, the goddess of flowers and vegetation.

1. Kalendae Apriles
2. a.d.IV.Non.Apr.
3. a.d.III.Non.Apr.
4. pridie Non.Apr.
5. Nonae Apriles
6. a.d.VIII.Id.Apr.
7. a.d.VII.Id.Apr.
8. a.d.VI.Id.Apr.
9. a.d.V.Id.Apr.
10. a.d.IV.Id.Apr.
11. a.d.III.Id.Apr.
12. pridie Id.Apr.
13. Idus Apriles
14. a.d.XVIII.Kal.Mai.
15. a.d.XVII.Kal.Mai.
16. a.d.XVI.Kal.Mai.
17. a.d.XV.Kal.Mai.
18. a.d.XIV.Kal.Mai.
19. a.d.XIII.Kal.Mai.
20. a.d.XII.Kal.Mai.
21. a.d.XI.Kal.Mai. Parilia (The birthday of Rome)
22. a.d.X.Kal.Mai.
23. a.d.IX.Kal.Mai. Vinalia
24. a.d.VIII.Kal.Mai.
25. a.d.VII.Kal.Mai. Robigalia
26. a.d.VI.Kal.Mai.
27. a.d.V.Kal.Mai.
28. a.d.IV.Kal.Mai. Floralia
29. a.d.III.Kal.Mai.
30. pridie Kal.Mai.

MAY (Mensis Maius)

There was similar confusion regarding the month of May, although it may be named for Maia, a goddess of growth and bounty. May was a time for work in the fields and anxious expectation of the harvest to follow. The month was associated with the underworld and was a time for purification; at the Lemuria, a festival of the dead, the house was purified of evil spirits. Not surprisingly, May was considered an unlucky month in which to marry.

1. Kalendae Maiae
2. a.d.VI.Non.Mai.
3. a.d.V.Non.Mai.
4. a.d.IV.Non.Mai.
5. a.d.III.Non.Mai.
6. pridie Non.Mai.
7. Nonae Maiae
8. a.d.VIII.Id.Mai.
9. a.d.VII.Id.Mai.
10. a.d.VI.Id.Mai.
11. a.d.V.Id.Mai.
12. a.d.IV.Id.Mai.
13. a.d.III.Id.Mai.
14. pridie Id.Mai.
15. Idus Maiae
16. a.d.XVII.Kal.Jun.
17. a.d.XVI.Kal.Jun.
18. a.d.XV.Kal.Jun.
19. a.d.XIV.Kal.Jun.
20. a.d.XIII.Kal.Jun.
21. a.d.XII.Kal.Jun.
22. a.d.XI.Kal.Jun.
23. a.d.X.Kal.Jun.
24. a.d.IX.Kal.Jun.
25. a.d.VIII.Kal.Jun.
26. a.d.VII.Kal.Jun.
27. a.d.VI.Kal.Jun.
28. a.d.V.Kal.Jun.
29. a.d.IV.Kal.Jun.
30. a.d.III.Kal.Jun.
31. pridie Kal.Jun.

JUNE (Mensis Junius)

Deriving its name from the goddess Juno, the first half of June was not regarded as an auspicious time to marry, probably because many of the days were dies religiosi. The Vestalia was celebrated then in honor of Vesta, the guardian of the hearth, and the temple opened to women worshipers. For the celebration, the Vestals made a sacred cake with water fetched from a sacred spring and carried in a vessel that could not be set on the ground without spilling. The Vestalia ended on the fifteenth, when the temple was swept clean and the debris carted off to the Tiber.

1. Kalendae Juniae
2. a.d.IV.Non.Jun.
3. a.d.III.Non.Jun.t
4. pridie Non.Jun.
5. Nonae Juniae
6. a.d.VIII.Id.Jun.
7. a.d.VII.Id.Jun.
8. a.d.VI.Id.Jun.
9. a.d.V.Id.Jun.
10. a.d.IV.Id.Jun.
11. a.d.III.Id.Jun.
12. pridie Id.Jun.
13. Idus Juniae
14. a.d.XVIII.Kal.Jul.
15. a.d.XVII.Kal.Jul.
16. a.d.XVI.Kal.Jul.
17. a.d.XV.Kal.Jul.
18. a.d.XIV.Kal.Jul.
19. a.d.XIII.Kal.Jul.
20. a.d.XII.Kal.Jul.
21. a.d.XI.Kal.Jul.
22. a.d.X.Kal.Jul.
23. a.d.IX.Kal.Jul.
24. a.d.VIII.Kal.Jul.
25. a.d.VII.Kal.Jul.
26. a.d.VI.Kal.Jul.
27. a.d.V.Kal.Jul.
28. a.d.IV.Kal.Jul.
29. a.d.III.Kal.Jul.
30. pridie Kal.Jul.

JULY (Mensis Julius)

Until it was renamed for Julius Caesar, this month was Quinctilis, the fifth month of the civil year. As the first six months of the year were named for their characteristics, the seasonal activities and deities who presided over them, the remaining months now begin to be identified numerically.

1. Kalendae Juliae
2. a.d.VI.Non.Jul.
3. a.d.V.Non.Jul.
4. a.d.IV.Non.Jul.
5. a.d.III.Non.Jul.
6. pridie Non.Jul.
7. Nonae Juliae
8. a.d.VIII.Id.Jul.
9. a.d.VII.Id.Jul.
10. a.d.VI.Id.Jul.
11. a.d.V.Id.Jul.
12. a.d.IV.Id.Jul.
13. a.d.III.Id.Jul.
14. pridie Id.Jul.
15. Idus Juliae
16. a.d.XVII.Kal.Aug.
17. a.d.XVI.Kal.Aug.
18. a.d.XV.Kal.Aug.
19. a.d.XIV.Kal.Aug.
20. a.d.XIII.Kal.Aug.
21. a.d.XII.Kal.Aug.
22. a.d.XI.Kal.Aug.
23. a.d.X.Kal.Aug.
24. a.d.IX.Kal.Aug.
25. a.d.VIII.Kal.Aug.
26. a.d.VII.Kal.Aug.
27. a.d.VI.Kal.Aug.
28. a.d.V.Kal.Aug.
29. a.d.IV.Kal.Aug.
30. a.d.III.Kal.Aug.
31. pridie Kal.Aug.

AUGUST (Mensis Augustus)

The sixth month of the old year, and renamed for Augustus, August was a time when the harvest almost was completed.

1. Kalendae Augustae
2. a.d.IV.Non.Aug.
3. a.d.III.Non.Aug.
4. pridie Non.Aug.
5. Nonae Augustae
6. a.d.VIII.Id.Aug.
7. a.d.VII.Id.Aug.
8. a.d.VI.Id.Aug.
9. a.d.V.Id.Aug.
10. a.d.IV.Id.Aug.
11. a.d.III.Id.Aug.
12. pridie Id.Aug.
13. Idus Augustae
14. a.d.XIX.Kal.Sept.
15. a.d.XVIII.Kal.Sept.
16. a.d.XVII.Kal.Sept.
17. a.d.XVI.Kal.Sept.
18. a.d.XV.Kal.Sept.
19. a.d.XIV.Kal.Sept.
20. a.d.XIII.Kal.Sept.
21. a.d.XII.Kal.Sept.
22. a.d.XI.Kal.Sept.
23. a.d.X.Kal.Sept.
24. a.d.IX.Kal.Sept.
25. a.d.VIII.Kal.Sept.
26. a.d.VII.Kal.Sept.
27. a.d.VI.Kal.Sept.
28. a.d.V.Kal.Sept.
29. a.d.IV.Kal.Sept.
30. a.d.III.Kal.Sept.
31. pridie Kal.Sept.

SEPTEMBER (Mensis September)

A time of comparative rest for the farmer, the harvest is in and the vintage not yet begun. The gods need not be invoked for their protection and favor, and there are few if any festivals. Instead, this is the time for the Ludi Romani, the oldest and most famous of the games.

1. Kalendae Septembres
2. a.d.IV.Non.Sept.
3. a.d.III.Non.Sept.
4. pridie Non.Sept.
5. Nonae Septembres
6. a.d.VIII.Id.Sept.
7. a.d.VII.Id.Sept.
8. a.d.VI.Id.Sept.
9. a.d.V.Id.Sept.
10. a.d.IV.Id.Sept.
11. a.d.III.Id.Sept.
12. pridie Id.Sept.
13. Idus Septembres
14. a.d.XVIII.Kal.Oct.
15. a.d.XVII.Kal.Oct.
16. a.d.XVI.Kal.Oct.
17. a.d.XV.Kal.Oct.
18. a.d.XIV.Kal.Oct.
19. a.d.XIII.Kal.Oct.
20. a.d.XII.Kal.Oct.
21. a.d.XI.Kal.Oct
22. a.d.X.Kal.Oct.
23. a.d.IX.Kal.Oct.
24. a.d.VIII.Kal.Oct.
25. a.d.VII.Kal.Oct.
26. a.d.VI.Kal.Oct.
27. a.d.V.Kal.Oct.
28. a.d.IV.Kal.Oct.
29. a.d.III.Kal.Oct.
30. pridie Kal.Oct.

OCTOBER (Mensis October)

October marked the end of the campaigning season that had begun in March, and there were ceremonies in honor of Mars. It also was time for the vintage, although only one festival marked its observance, which shows how late viticulture was introduced to Italy.

1. Kalendae Octobres
2. a.d.VI.Non.Oct.
3. a.d.V.Non.Oct.
4. a.d.IV.Non.Oct.
5. a.d.III.Non.Oct.
6. pridie Non.Oct.
7. Nonae Octobres
8. a.d.VIII.Id.Oct.
9. a.d.VII.Id.Oct.
10. a.d.VI.Id.Oct.
11. a.d.V.Id.Oct.
12. a.d.IV.Id.Oct.
13. a.d.III.Id.Oct.
14. pridie Id.Oct.
15. Idus Octobres
16. a.d.XVII.Kal.Nov.
17. a.d.XVI.Kal.Nov.
18. a.d.XV.Kal.Nov.
19. a.d.XIV.Kal.Nov.
20. a.d.XIII.Kal.Nov.
21. a.d.XII.Kal.Nov.
22. a.d.XI.Kal.Nov.
23. a.d.X.Kal.Nov.
24. a.d.IX.Kal.Nov.
25. a.d.VIII.Kal.Nov.
26. a.d.VII.Kal.Nov.
27. a.d.VI.Kal.Nov.
28. a.d.V.Kal.Nov.
29. a.d.IV.Kal.Nov.
30. a.d.III.Kal.Nov.
31. pridie Kal.Nov.

NOVEMBER (Mensis November)

The least important month for religious festivals, November did celebrate the Ludi Plebeii, a time of performances and Circus games that extended from the 4th to the 17th.

1. Kalendae Novembres
2. a.d.IV.Non.Nov.
3. a.d.III.Non.Nov.
4. pridie Non.Nov.
5. Nonae Novembres
6. a.d.VIII.Id.Nov.
7. a.d.VII.Id.Nov.
8. a.d.VI.Id.Nov.
9. a.d.V.Id.Nov.
10. a.d.IV.Id.Nov.
11. a.d.III.Id.Nov.
12. pridie Id.Nov.
13. Idus Novembres
14. a.d.XVIII.Kal.Dec.
15. a.d.XVII.Kal.Dec.
16. a.d.XVI.Kal.Dec.
17. a.d.XV.Kal.Dec.
18. a.d.XIV.Kal.Dec.
19. a.d.XIII.Kal.Dec.
20. a.d.XII.Kal.Dec.
21. a.d.XI.Kal.Dec.
22. a.d.X.Kal.Dec.
23. a.d.IX.Kal.Dec.
24. a.d.VIII.Kal.Dec.
25. a.d.VII.Kal.Dec.
26. a.d.VI.Kal.Dec.
27. a.d.V.Kal.Dec.
28. a.d.IV.Kal.Dec.
29. a.d.III.Kal.Dec.
30. pridie Kal.Dec.

DECEMBER (Mensis December)

Work in the fields now was less demanding, and December saw the celebration of a number of festivals, the most well-known of which is the Saturnalia. There also was a celebration of the Good Goddess. Attended only by the Vestal Virgins and women celebrants, the Bona Dea was a private ceremony so mysterious that even the name of the goddess could not be revealed. In 62 BC, when it was held in the house of Julius Caesar, who was praetor at the time, its secret rites were desecrated by Publius Clodius Pulcher. In an audacious attempt to meet with Caesar's wife Pompeia, with whom he was alleged to be having an affair, Clodius gained admission dressed as a woman. There was a scandal. Caesar divorced Pompeia as not being above suspicion, and Clodius was put on trial for sacrilege. Acquited by a bribed jury, Clodius never forgave Cicero, whom he had supported in his prosecution of Catiline the year before, for giving evidence against him. The activities of the Bona Dea later were satirized by Juvenal (II.86ff, VI.314ff).

1. Kalendae Decembres
2. a.d.IV.Non.Dec.
3. a.d.III.Non.Dec.
4. pridie Non.Dec.
5. Nonae Decembres
6. a.d.VIII.Id.Dec.
7. a.d.VII.Id.Dec.
8. a.d.VI.Id.Dec.
9. a.d.V.Id.Dec.
10. a.d.IV.Id.Dec.
11. a.d.III.Id.Dec.
12. pridie Id.Dec.
13. Idus Decembres
14. a.d.XIX.Kal.Jan.
15. a.d.XVIII.Kal.Jan.
16. a.d.XVII.Kal.Jan.
17. a.d.XVI.Kal.Jan Saturnalia
18. a.d.XV.Kal.Jan.
19. a.d.XIV.Kal.Jan.
20. a.d.XIII.Kal.Jan.
21. a.d.XII.Kal.Jan.
22. a.d.XI.Kal.Jan.
23. a.d.X.Kal.Jan.
24. a.d.IX.Kal.Jan.
25. a.d.VIII.Kal.Jan.
26. a.d.VII.Kal.Jan.
27. a.d.VI.Kal.Jan.
28. a.d.V.Kal.Jan.
29. a.d.IV.Kal.Jan.
30. a.d.III.Kal.Jan.
31. pridie Kal.Jan.


References: Marcus Porcius Cato: On Agriculture and Marcus Terentius Varro: On Agriculture (1935) translated by William Davis Hooper, revised by Harrison Boyd Ash (Loeb Classical Library); Lucius Junius Moderatus Columella: On Agriculture (1941-) translated by Harrison Boyd Ash and by E. S. Forster and Edward H. Heffner (Loeb Classical Library); Caesar's Calendar (2008) by Denis Feeney.

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