All nations, before the just length of the Solar year was known, reckoned months by the course of the moon; and years by the [47] returns of winter and summer, spring and autumn: and in making Calendars for their Festivals, reckoned thirty days to a Lunar month, and twelve Lunar months to a year; taking the nearest round numbers: whence came the division of the Ecliptic into 360 degrees. So in the time of Noah's flood, when the Moon could not be seen, Noah reckoned thirty days to a month: but if the Moon appeared a day or two before the end of the month, [48] they began the next month with the first day of her appearing: and this was done generally, 'till the Egyptians of Thebais found the length of the Solar year. So [49] Diodorus tells us that the Egyptians of Thebais use no intercalary months, nor subduct any days [from the month] as is done by most of the Greeks. And [50] Cicero, est consuetudo Siculorum cæterorumque Græcorum, quod suos dies mensesque congruere volunt cum Solis Lunæque ratione, ut nonnumquam siquid discrepet, eximant unum aliquem diem aut summum biduum ex mense [civili dierum triginta] quos illi εξαιρεσιμους dies nominant. And Proclus, upon Hesiod's τριακας mentions the same thing. And [51] Geminus: Προθεσις γαρ ην τοις αρχαιοις, τους μεν μηνας αγειν κατα σεληνην, τους δε ενιαυτους καθ' ‛ηλιον. Το γαρ ‛υπο των νομων, και των χρησμων παραγγελλομενον, το θυειν κατα γ', ηγουν τα πατρια, μηνας, ‛ημερας, ενιαυτους: τουτο διελαβον απαντες ‛οι ‛Ελληνες τωι τους μεν ‛ενιαυτους συμφωνως αγειν τωι ‛ηλιωι· τας δε ‛ημερας και τους μηνας τηι σεληνη. εστι δε το μεν καθ' ‛ηλιον αγειν τους ενιαυτους, το περι τας αυτας ‛ωρας του ενιαυτου τας αυτας θυσιας τοις θεοις επιτελειθαι, και την μεν εαρινην θυσιαν δια παντος κατα το εαρ συντελειθαι· την δε θερινην, κατα το θερος· ‛ομοιως δε και κατα τους λοιπους καιρους του ετους τας αυτας θυσιας πιπτειν. Τουτο γαρ ‛υπελαβον προσηνες, και κεχαρισμενον ειναι τοις θεοις. Τουτο δ' αλλως ουκ αν δυναιτο γενεσθαι, ει μη ‛αι τροπαι, και ‛αι ισημεριαι περι τους αυτους τοπους γιγνοιντο. Το δε κατα σεληνην αγειν τας ‛ημερας, τοιουτον εστι· το ακολουθως τοις της σεληνης φωτισμοις τας προσηγοριας των ‛ημερων γινεσθαι. απο γαρ των της σεληνης φωτισμων ‛αι προσηγοριαι των ‛ημερων κατωνομασθησαν. Εν ‛ηι μεν γαρ ‛ημεραι νεα ‛η σεληνη φαινεται, κατα συναλοιφην νεομηνια προσηγορευθη· εν ‛ηι δε ‛ημεραι την δευτεραν φασιν ποιειται, δευτεραν προσηγορευσαν· την δε κατα μεσον του μηνος γινομενην φασιν της σεληνης, απο αυτου του συμβαινοντος διχομηνιαν εκαλεσαν. και καθολου δε πασας τας ‛ημερας απο των της σεληνης φωτισματων προσωνομασαν. ‛οθεν και την τριακοστην του μηνος ‛ημεραν εσχατην ουσαν απο αυτου του συμβαινοντος τριακαδα εκαλεσαν. Propositum enim fuit veteribus, menses quidem agere secundum Lunam, annos vero secundum Solem. Quod enim a legibus & Oraculis præcipiebatur, ut sacrificarent secundum tria, videlicet patria, menses, dies, annos; hoc ita distincte faciebant universi Græci, ut annos agerent congruenter cum Sole, dies vero & menses cum Luna. Porro secundum Solem annos agere, est circa easdem tempestates anni eadem sacrificia Diis perfici, & vernum sacrificium semper in vere consummari, æstivum autem in æstate: similiter & in reliquis anni temporibus eadem sacrificia cadere. Hoc enim putabant acceptum & gratum esse Diis. Hoc autem aliter fieri non posset nisi conversiones solstitiales & æquinoctia in iisdem Zodiaci locis fierent. Secundum Lunam vero dies agere est tale ut congruant cum Lunæ illuminationibus appellationes dierum. Nam a Lunæ illuminationibus appellationes dierum sunt denominatæ. In qua enim die Luna apparet nova, ea per Synalœphen, seu compositionem νεομηνια id est, Novilunium appellatur. In qua vero die secundam facit apparitionem, eam secundam Lunam vocarunt. Apparitionem Lunæ quæ circa medium mensis fit, ab ipso eventu διχομηνιαν, id est medietatem mensis nominarunt. Ac summatim, omnes dies a Lunæ illuminationibus denominarunt. Unde etiam tricesimam mensis diem, cum ultima sit, ab ipso eventu τριακαδα vocarunt.
The ancient Calendar year of the Greeks consisted therefore of twelve Lunar months, and every month of thirty days: and these years and months they corrected from time to time, by the courses of the Sun and Moon, omitting a day or two in the month, as often as they found the month too long for the course of the Moon; and adding a month to the year, as often as they found the twelve Lunar months too short for the return of the four seasons. Cleobulus, [52] one of the seven wise men of Greece, alluded to this year of the Greeks, in his Parable of one father who had twelve sons, each of which had thirty daughters half white and half black: and Thales [53] called the last day of the month τριακαδα, the thirtieth: and Solon counted the ten last days of the month backward from the thirtieth, calling that day ενην και νεαν, the old and the new, or the last day of the old month and the first day of the new: for he introduced months of 29 and 30 days alternately, making the thirtieth day of every other month to be the first day of the next month.
To the twelve Lunar months [54] the ancient Greeks added a thirteenth, every other year, which made their Dieteris; and because this reckoning made their year too long by a month in eight years, they omitted an intercalary month once in eight years, which made their Octaeteris, one half of which was their Tetraeteris: And these Periods seem to have been almost as old as the religions of Greece, being used in divers of their Sacra. The [55] Octaeteris was the Annus magnus of Cadmus and Minos, and seems to have been brought into Greece and Crete by the Phœnicians, who came thither with Cadmus and Europa, and to have continued 'till after the days of Herodotus: for in counting the length of seventy years [56], he reckons thirty days to a Lunar month, and twelve such months, or 360 days, to the ordinary year, without the intercalary months, and 25 such months to the Dieteris: and according to the number of days in the Calendar