By Water & Blood

Chapter 14: Caesar's Reform of the Calendar

"But there was a time when on account of superstition all intercalation was omitted; sometimes indeed through the favor of the priests, who wished the days of the year to be deliberately advanced or diminished for the tax-farmers, now an increase, now a retraction of days came about, and under the appearance of observance a greater occasion of confusion emerged. But afterward Gaius Caesar forced all this inconstancy of times, still vague and uncertain, into the order of a fixed definition, with Marcus Flavius the scribe assisting him, who so reported the individual written days to the dictator that both their order could most easily be found and, when found, a sure status might persist. Therefore Gaius Caesar, about to begin the outset of a new arrangement, consumed all the days which could still make confusion, and by this means it came about that the last year of confusion was extended to four hundred and forty-three days.

After this, imitating the Egyptians, alone conscious of all divine matters, he strove to direct the year according to the number of the sun, which completes its course in three hundred and sixty-five days and a quarter. For just as the lunar year is a month, because the moon consumes a little less than a month in the circuit of the zodiac, so the year of the sun is to be gathered in this number of days which it completes while it turns itself again to that sign from which it departed; whence it is called the turning year and is held to be great, while the year of the moon is thought short. Virgil has embraced both of these: 'Meanwhile the sun rolls round the great year.' Hence also Ateius Capito thinks the year so called from the circuit of time, because the ancients used to put an for circum, as Cato in the Origins: 'the plowman an terminum,' that is around the boundary, and ambire is said for circumire.

Julius Caesar therefore added ten days over and above the old observance, so that three hundred and sixty-five days in which the sun traverses the zodiac might make the year; and lest the quarter be lacking, he established that in every fourth year the priests who cared for months and days should intercalate one day, in that month of course and place where also among the ancients the month was intercalated, that is before the five last days of the month of February, and he resolved that it should be named the bissextile. But the ten days which we have said were added by him he distributed by this arrangement. Into January and Sextilis and December he inserted two days each; into April, June, September, November one each; but he added no day to the month of February, lest the religion of the underworld gods be changed, and he preserved the former status for March, May, Quintilis, October, because they were of a sufficiently full number, that is of thirty-one days each. Therefore they also have Nones on the seventh, as Numa established, because Julius changed nothing in these; but January, Sextilis, December, to which Caesar added two days, although after Caesar they began to have thirty-one, nevertheless have Nones on the fifth, and from those Ides the following Kalends return to the nineteenth, because Caesar wished to insert the days he added neither before the Nones nor before the Ides, lest he corrupt the religion of the Nones or Ides, which was on a fixed day, by a novel postponement. But neither did he wish to insert them immediately after the Ides, lest the proclamation of any holidays be violated, but when the holidays of each month had been completed he made a place for the incoming days.

And to January indeed he gave the days which we call the fourth and third before the Kalends of February; to April the sixth before the Kalends of May; to June the third before the Kalends of July; to August the fourth and third before the Kalends of September; to September the third before the Kalends of October; to November the third before the Kalends of December; but to December the fourth and third before the Kalends of January. Thus it came about that whereas all these months to which he added days had before this arrangement had the Kalends of the following month returning to the seventeenth, afterward from the increase of the added days those which received two had a return of the Kalends to the nineteenth, those which received one to the eighteenth. Yet the order of the holidays of each month was preserved. For if roughly the third day from the Ides was a festival or holiday for anyone and was then called the sixteenth before the Kalends, even after the addition of days the same religion was preserved, that it be celebrated on the third day from the Ides, although from the increase it was no longer called the sixteenth before the Kalends but the seventeenth, if one was added, or the eighteenth, if two were added. For therefore he inserted the new days near the end of each month, where he found the end of all the holidays that were in the month, and he marked all the days added by himself as court days (fasti), that he might give greater liberty to legal actions, and he instituted not only no unlucky day but not even any assembly day among the added days, lest the addition increase the ambition of magistrates.

Thus Caesar published the civil year, constituted by measurements brought to the file, by an edict openly posted; and the error could have stood thus far, had not the priests made a new error for themselves from the very correction. For when it was proper to intercalate the day which is made from the quarters when every fourth year had been completed, before the fifth began, they intercalated not when the fourth was completed but when it was beginning. This error lasted thirty-six years, in which years twelve days were intercalated when nine ought to have been intercalated. But this error too, late discovered, Augustus corrected, who ordered twelve years to be passed without an intercalary day, so that those three days which through thirty-six years had grown by the fault of priestly haste might be absorbed in the following twelve years with no day intercalated. After this he ordered one day to be intercalated according to Caesar's arrangement at the beginning of every fifth year, and committed this whole order by inscription on a bronze tablet to eternal custody."