Macrobius

"All that is known for certain of Macrobius is that he had a son [...] and that he was not a native of Italy but had been 'born under an alien sky' (Saturnalia preface)" although he may be the same Macrobius identified as vicar of Spain in 399 CE, Proconsul of Africa in 410 CE, and Grand Chamberlain in 422 CE (Davies p. 1).

Relevant Excerpts

Commentary on the Dream of Scipio

[trans. William Harris Stahl, Columbia University Press 1990]

12.12 - 12.18

[Stahl pp.136-137]

Members of the Orphic sect believe that material mind is represented by Bacchus himself, who, born of a single parent, is divided into separate parts. In their sacred rites they portray him as being torn to pieces at the hands of angry Titans and arising again from his buried limbs alive and sound, their reason being that nous or Mind, by offering its undivided substance to be divided, and again, by returning from its divided state to the indivisible, both fulfills its worldly functions and does not forsake its secret nature.

By the impulse of the first weight the soul, having started on its downward course from the intersection of the zodiac and the Milky Way to the successive spheres lying beneath, as it passes through these spheres, not only takes on the aforementioned envelopment in each sphere by approaching a luminous body, but also acquires each of the attributes which it will exercise later. In the sphere of Saturn it obtains reason and understanding, called logistikon and theoretikon; in Jupiter's sphere, the power to act, called praktikon; in Mars' sphere, a bold spirit or thymikon; in the sun's sphere, sense-perception and imagination, aisthetikon and phantastikon; in Venus' sphere, the impulse of passion, epithymetikon; in Mercury's sphere, the ability to speak and interpret, hermeneutikon; and in the lunar sphere, the function of molding and increasing bodies, phytikon. This last function, being the farthest removed from the gods, is the first in us and all the earthly creation; inasmuch as our body represents the dregs of what is divine, it is therefore the first substance of the creature. The difference between terrestrial and supernal bodies (I am speaking of the sky and stars and the other components) lies in this, that the latter have been summoned upwards to the abode of the soul and have gained immortality by the very nature of that region and by copying the perfection of their high estate; but to our terrestrial bodies the soul is drawn downwards, and here it is believed to be dead while it is shut up in a perishable region and the abode of mortality.

Be not disturbed that in reference to the soul, which we say is immortal, we so often use the term "death." In truth, the soul is not destroyed by its death but is overwhelmed for a time; nor does it surrender the privilege of immortality because of its lowly sojourn, for when it has rid itself completely of all taint of evil and has deserved to be sublimated, it again leaves the body and, fully recovering its former state, returns to the splendor of everlasting life. The distinction between the soul in life and in death, which the learning and wisdom of Cicero drew forth from the sanctuaries of philosophy, is now, I believe, perfectly clear.

Saturnalia

[trans. Percival Vaughan Davies, Columbia University Press 1969]

"the Saturnalia has preserved much anonymous and other material which would otherwise have been lost; and, in addition to its value on this account, there is also the intrinsic interest of the Vergilian criticism and of the varied antiquarian lore which the book contains." (Davies p.3)

The Saturnalia is a dialogue spread across many days of the festival. During the first day, in Book I, "the chief speaker is Praetextatus, who continues with an account of the development of the Roman calendar and a detailed exposition of the theological doctrine of syncretism, which makes all the gods of the pagan pantheon manifestations of a single divine power, the sun" (Davies p.14)

Book I, 17.34

[Davies p. 120]

So too he [Apollo] is called "Phanes," because he gives light (φαίνειν). And "Phaneos," that is, "coming new (φαίνεται νέος) to our eyes," since the sun renews itself each day; and this is why Vergil uses the phrase "when the morning is new."

Book I, 17.46

[Davies p.121]

Apollo "Eleleus"* is so called from his wheeling movement (ἐλίττεσθαι) round the earth, since the sun seems, as it were, to roll round the earth in an unending orbit--as Euripides says:

O Sun, wheeling thy flaming chariot with its swift steeds

or else because he goes round as a vast mass (συναλισθέντος) of fire--in the words of Empedocles:

Since, massed (ἀναλισθεὶς) into a ball, he travels round the great expanse of heaven.

Plato,** also deriving the epithet from the word which means to "mass" or "collect," explains it as indicating that the sun at its rising collects men and gathers them together.

Translator's Footnotes:

*: This epithet is usually applied to Dionysus and refers to the cries of the Bacchanals. See Ovid Metamorphoses 4.15.

**: Cratylus 409a, where Socrates suggests that the derivation of ἥλιος would be clearer if the Doric form, ἅλιος, were used.

Book I, 17.42

[Davies p. 121]

Apollo has been called "Father of the People," not as worshiped according to the particular religious usage of a single race or state but as the generating cause of all things, since the sun, by drying up moisture, is the universal cause of generation--in the words of Orpheus:

Having the mind and wise counsel of a father

and it is for this reason that we also call Janus "Father" and worship the sun under that name.

Book I, 18.1-18.6

[Davies pp.128-129]

What we have said of Apollo may be taken to apply to Liber also. Certainly Aristotle, writing in his Inquiries into the Nature of the Divine, states that Apollo and Liber Pater are one and the same god, and among the many proofs of this statement he also says that the Ligyreans in Thrace have a shrine dedicated to Liber from which oracles are given. In this shrine, the soothsayers drink large draughts of wine before delivering their prophecies, just as in the temple of Apollo at Claros water is drunk before the oracles are pronounced.
Moreover, among the Spartans, at the celebrations of the rites in honor of Apollo called the Hyacinthia, garlands of ivy are worn, as in the worship of Bacchus. Likewise the Boeotians, although they speak of Mount Parnassus as sacred to Apollo, nevertheless pay honor there both to the Delphic oracle and to the caves of Bacchus as dedicated to a single god, so that both Apollo and Liber Pater are worshiped on the same mountain. This is confirmed by Varro and Granius Flaccus; and this too is what Euripides tells us in the lines:

Dionysus equipped with thyrsus and clad in skins of fawns leaps dancing down Parnassus among the pines.

It is on Mount Parnassus that a festival of Bacchus is held every other year, at which, it is said, many bands of Satyrs are seen and their characteristic voices are frequently heard, and likewise the clashing of cymbals often strikes men's ears. And--that no one may suppose Parnassus to be sacred to two different gods--the following line from the Licymnius of Euripides also indicates that Apollo and Liber are one and the same god:

Lord Bacchus, Lover of the Laurel, Apollo the Healer, making sweet music on the lyre

and Aeschylus writes to the same effect:

Apollo, the ivy-crowned, the Bacchic god, the Seer.

Book I, 18.8-18.10

[Davies p.129]

In the performance of sacred rites a mysterious rule of religion ordains that the sun shall be called Apollo when it is in the upper hemisphere, that is to say, by day, and be held to be Dionysus, or Liber Pater, when it is in the lower hemisphere, that is to say, at night. Likewise, statues of Liber Pater represent him sometimes as a child and sometimes as a young man; again, as a man with a beard and also as an old man, as for example the statue of the god which the Greeks call Bassareus and Briseus, and that which in Campania the Neapolitans worship under the name Hebon. These differences in age have reference to the sun, for at the winter solstice the sun would seem to be a little child, like that which the Egyptians bring forth from a shrine on an appointed day, since the day is then at its shortest and the god is accordingly shown as a tiny infant. Afterward, however, as the days go on and lengthen, the sun at the spring equinox acquires strength in a way comparable to growth to adolescence, and so the god is given the appearance of a young man. Subsequently, he is represented in full maturity, with a beard, at the summer solstice, when the sun's growth is completed. After that, the days shorten, as though with the approach of his old age--hence the fourth of the figures by which the god is portrayed.

Book I, 18.12-18.22

[Davies pp.130-131]

Orpheus too intended the following passage to be understood to refer to the sun:

Melting the divine ether which aforetime was without motion, he [the Creator] brought up and displayed a most beautiful sight to the Gods; him, whom men now call by the names of Phanes and Dionysus and the lord Eubouleus and Antauges seen afar (for on earth some men give him one name and some another). He was the first to come forth into light, and he was called Dionysus, because he wheels (dineitai) throughout the boundless length of Olympus, but with change he took another name, having titles manifold to fit each change according to the seasons of changing time.

Orpheus here has called the sun "Phanes" (φανερός), from its light and enlightening, for the sun sees all and is seen by all. The name Dionysus is derived, as the soothsayer himself says, from the fact that the sun wheels around in an orbit. Cleanthes writes that the name Dionysus is derived from the Greek verb meaning "to complete" (διανύσαι), because the sun in its daily course from its rising to its setting, making the day and the night, completes the circuit of the heavens. For the physicists Dionysus is "the mind of Zeus" (Διὸς νοῦς), since they hold that the sun is the mind of the universe, and by the universe they mean the heavens - which they call Jupiter - and that is why Aratus, when about to speak of the heavens, says:

From Zeus be our beginnings.

The Romans call the sun Liber, because he is free (liber) to wander - as Naevius puts it:

Here where the wandering sun flings loose his fiery reins and drives nearer to the earth.

The Orphic verses, too, by calling the sun "Eubouleus," indicate that he is the patron of "good counsel"; for, if counsel is the offspring of mind and if, in the opinion of our authorities, the sun is the mind of the universe from which the first beginning of intelligence is diffused among mankind, then the sun is rightly believed to preside over good counsel.
In the line:

The sun, which men also call by name Dionysus

Orpheus manifestly declares that Liber is the sun, and the meaning here is certainly quite clear; but the following line from the same poet is more difficult:

One Zeus, one Hades, one Sun, one Dionysus.

The warrant for this last line rest on an oracle of Apollo of Claros, wherein yet another name is given to the sun; which is called, within the space of the same sacred verses by several names, including that of Iao. For when Apollo of Claros was asked who among the gods was to be regarded as the god called Iao, he replied:

Those who have learned the mysteries should hide the unsearchable secrets, but, if the understanding is small and the mind weak, then ponder this: that Iao is the supreme god of all gods; in winter, Hades; at spring's beginning, Zeus; the Sun in summer, and in autumn, the splendid Iao.

For the meaning of this Oracle and for the explanation, of the deity and his name, which identifies Iao with Liber Pater and the sun, our authority is Cornelius Labeo in his book entitled On the Oracle of Apollo of Claros.
Again, Orpheus, pointing out that Liber and the sun are one and the same god, writes as follows of the ornaments and vestments worn by Liber at the ceremonies performed in his honor:

All these things duly perform right early, having arrayed the body of the god with his apparel, in imitation of the renowned sun. First, then, to represent the fiery rays cast about him a crimson robe, like to fire. Moreover, above it fasten on the right shoulder a broad, dappled skin of a fawn, the many-spotted hide of the beast, to represent the sparkling stars and the sacred sky. Then, over the fawn-skin cast a golden belt, all-gleaming, that he wear it around his breast, a mighty sign of the sun, when straightway he leaps up, shining, from the boundaries of earth and smites with his golden rays the stream of Ocean; and unspeakably great is his light, and mingled with dew the light gleams as it wheels in eddies in circles before the god. and as a belt below his his measureless breast is seen the encircling Ocean, a great wonder to behold.