Roger Pearse responded to my post on Sol Invictus, and made some very good points.
Aurelian did institite games of the sun (agones solis) in October. The calendar of Philocalus does not give any Christian festivals, so I think we can take it that Natalis Invicti is a state festival of pagan origin. The remark of Julian about the Heliaia on that date — the attribution to Numa is unevidenced, as you say — confirms that such a festival did occur. If you look at the Chronography calendar, you will notice that all the old festivals have the same number of chariot races, while those created in late antiquity have strange numbers like 24. This suggests that the 25 Dec. festival is also a late creation.
There is also the question of what “natalis” means. It could mean birthday; but also it can mean “anniversary of the dedication of a temple”. This seems to be the meaning for other “natalis” in the calendar. We know that Aurelian dedicated the temple of Sol Invictus. Thus we would get a festival on the anniversary of the dedication of the temple, and thus the idea that the festival was created at the same time by Aurelian.
On the other hand, the idea that 25 Dec. is the “new sun” or “birth of the sun” appears in Latin literature generally. The astrologer Antiochus of Athens describes it as the birthday of the sun in his calendar of heavenly events, and he may have lived in the 1st or 2nd centuries. If so, perhaps Natalis has its usual meaning.
But it seems to me that there is a pile of uncertainty in all this.
The idea that Christmas was celebrated on 25 Dec. to stamp on a pagan festival is asserted half a century later by Chrysostom, if I remember correctly.
I think Roger makes a good counterargument against the idea that the Festival of Sol Invictus was not instituted until the fourth century, it does seem reasonable that Emperor Aurelian did institute a Festival on December 25 in 274 A.D. However, as Roger says, this is uncertain and all we can say for sure is that in the fourth century a Festival did exist.
In terms of Antiochus of Athens, I was looking at his calendar here (Roger is providing translations on his blog) and to me the calendar appears to be purely astronomical in nature and has nothing to do with mythology, implying that when Antiochus uses the term “birthday of the Sun (ἡλίου γενέθλιον) Light increases” on December 25, that this is just referring to the winter solstice to when daylight begins getting longer, (thanks Roger for the correction) and not a pagan festival or birth of a god. Antiochus places the vernal equinox on March 22, but he also indicates that the Autumnul equinox occurred on September 25, so it would make sense that he would believe that the winter solstice was on December 25, exactly 3 months later. He actually does say that winter begins on December 22, but that light begins to increase on the 25th (thanks to Roger for pointing this out.)
I did some research using the TLG database and found some interesting quotations, which I think prove my point that Antiochus is here simply referring to the winter solstice to when daylight begins to finally increase and not any pagan or mythological Festival or birth.
The first of our two authors is Plutarch (wrote c100 AD) in his Isis and Osiris section 52 (372A-C) found here he says that, according to the Egyptians, the birth of the “eyes of Horus” occurred sometime in the summer (when the month of Epip occurred).
In the sacred hymns of Osiris they call upon him who is hidden in the arms of the Sun; and on the thirtieth of the month Epiphi they celebrate the birthday of the Eyes of Horus, at the time when the Moon and the Sun are in a perfectly straight line, since they regard not only the Moon but also the Sun as the eye and light of Horus.
He goes on to say that the birth of the “staff of the Sun”, according to the Egyptians, occurred near the autumnal equinox. He uses the same term “ἡλίου γενέθλιον” that Antiochus of Athens used:
On the waning of the month Phaophi they conduct the birthday of the Staff of the Sun [ἡλίου γενέθλιον] following upon the autumnal equinox, and by this they declare, as it were, that he is in need of support and strength, since he becomes lacking in warmth and light, and undergoes decline, and is carried away from us to one side.
Plutarch then references the winter solstice and Egyptian celebrations concerning the sun, none of which have to do with its birth.
Moreover, at the time of the winter solstice they lead the cow seven times around the temple of the Sun and this circumambulation is called the Seeking for Osiris, since the Goddess in the winter-time yearns for water; so many times do they go around, because in the seventh month the Sun completes the transition from the winter solstice to the summer solstice. It is said also that Horus, the son of Isis, offered sacrifice to the Sun first of all on the fourth day of the month, as is written in the records entitled the Birthdays of Horus.
Like Macrobius in his Saturnalia Egyptians apparently liked to associate many different gods with the sun:
Every day they make a tripleoffering of incense to the Sun, an offering of resin at sunrise, of myrrh at midday, and of the so‑called cyphi at sunset; the reason which underlies each one of these offerings I will describe later. They think that by means of all these they supplicate and serve the Sun. Yet, what need is there to collect many such things? There are some who without reservation assert that Osiris is the Sun and is called the Dog-star (Sirius) by the Greeks even if among the Egyptians the addition of the article has created some ambiguity in regard to the name; and there are those who declare that Isis is none other than the Moon; for this reason it is said that the statues of Isis that bear horns are imitations of the crescent moon, and in her dark garments are shown the concealments and the obscurations in which she in her yearning pursues the Sun. For this reason also they call upon the Moon in love affairs, and Eudoxus asserts that Isis is a deity who presides over love affairs. These people may lay claim to a certain plausibility, but no one should listen for a moment to those who make Typhon to be the Sun.
Plutarch at least shows that there were different “births” of the Sun throughout the year, and they appear to refer to different solar phases, but also have connections to pagan practices. Though according to Plutarch the birth of the Sun does not appear to occur on the winter solstice, but on the Autumnal Equinox ( this however is inferred and not certain).
Much more relevant is our second author, Hephaestion of Thebes (wrote 4th century AD). He also mentions the birth of the sun in his untranslated (in English at least) (apparently translated by Robert Schmidt, but I do not have a copy) astronomical writing Apotelesmatica, which according to Roger Pearse has been translated by In this work he quotes Antiochus of Athens where Antiochus uses the term “γενέθλιον”!
But Antiochus of Athens says also that this method has a certain truth to it. “Observe,” he says “on a given day that the Moon is born and to this number add 180 and always deduct 29 from the birthday [γενέθλιον] of the month…
Apotelesmatica of Hephaeston of Thebes p.82 lines 21-24
Antiochus here appears to use the term “birthday” or “γενέθλιον” to refer to the start of a month. Haphaestion uses “γενέθλιον” 17 times in this work, to refer to the Sun (p.83, line 27), the Moon (p.85 line 8), a month (p.82 line 24), and a even a day (P. 83 line 28).
It seems clear that Haphaestion and Antiochus used the term “γενέθλιον” or “birthday” not to refer to the birth of a god or the celebration of the birth, but simply to the start of a new astronomical phase, either solar, lunar, or monthly, or daily. Thus it makes perfect sense that Antiochus used the phrase “Birthday of the Sun. Light increases.” on the winter solstice on the day that daylight begins to increase December 25, which refers to the start of the new solar phase, and not to the birth of a god or to any Festival.
As for the quote by John Chrysostom referenced by Roger above, I cannot find it, but it does sound familiar to me. Anyone know where its location is?
The webpage on Robert Schmidt’s website references Antiochus of Athens’ “Thesaurus” which apparently gives definitions all sorts of astronomical terms. Maybe it has a definition for γενέθλιον?