The Milky Way river and the Twins were probably forever fixed together as a mind pattern. Once, a long time ago, at the northern spring equinox the Sun would quickly have crossed over the equator from the southern hemisphere to the northern hemisphere and at that ancient time his journey went across the Milky Way. The cold waters of winter changed into a warm dry land.

... 'The earth rises up from the sea again, and is green and beautiful and things grow without sowing ...

The Gemini twins could have personified the pair of newborn halves of the year climbing up on the far bank of the galactic river. Fire (Sun) could never survive wading across a river. Therefore some trick had to be used and the method of his transportation could have been for instance inside a fish or similar:

... And then the bone spoke; it was there in the fork of the tree: Why do you want a mere bone, a round thing in the branches of a tree? said the head of One Hunaphu when it spoke to the maiden. You don't want it, she was told. I do want it, said the maiden. Very well. Stretch out your right hand here, so I can see it, said the bone.

Yes, said the maiden. She stretched out her right hand, up there in front of the bone. And then the bone spit out its saliva, which landed squarely in the hand of the maiden. And then she looked in her hand, she inspected it right away, but the bone's saliva wasn't in her hand. It is just a sign I have given you, my saliva, my spittle. This, my head, has nothing on it - just bone, nothing of meat. It's just the same with the head of a great lord: it's just the flesh that makes his face look good. And when he dies, people get frightened by his bones. After that, his son is like his saliva, his spittle, in his being, whether it be the son of a lord or the son of a craftsman, an orator.

The father does not disappear, but goes on being fulfilled. Neither dimmed nor destroyed is the face of a lord, a warrior, craftsman, an orator. Rather, he will leave his daughters and sons. So it is that I have done likewise through you. Now go up there on the face of the earth ...

The old Sun disappeared at one end of Milky Way River but he would be freshly born again (reincarnated) after the June solstice. Thus the Charioteer (Auriga) on wintery side of the river had no Sun horse but instead carried a sign of the hairy Goat on his back:

... All 'change stations' are found invariably in two regions: one in the South between Scorpius and Sagittarius, the other in the North between Gemini and Taurus; and this is valid through time and space, from Babylon to Nicaragua. Why was it ever done in the first place? Because of the Galaxy, which has its crossroads with the ecliptic between Sagittarius and Scorpius in the South, and between Gemini and Taurus in the North.

... Men's spirits were thought to dwell in the Milky Way between incarnations. This conception has been handed down as an Orphic and Pythagorean tradition fitting into the frame of the migration of the soul. Macrobius, who has provided the broadest report on the matter, has it that souls ascend by way of Capricorn, and then, in order to be reborn, descend again through the 'Gate of Cancer'.

Macrobius talks of signs; the constellations rising at the solstices in his time (and still in ours) were Gemini and Sagittarius: the 'Gate of Cancer' means Gemini. In fact, he states explicitly (I,12.5) that this 'Gate' is 'where the Zodiac and the Milky Way intersect'.  

Far away, the Mangaians of old (Austral Islands, Polynesia), who kept the precessional clock running instead of switching over to 'signs', claim that only at the evening of the solstitial days can spirits enter heaven, the inhabitants of the northern parts of the island at one solstice, the dwellers in the south at the other ...

Considering the fact that the crossroads of ecliptic and Galaxy are crisis-resistant, that is, not concerned with the Precession, the reader may want to know why the Mangaians thought they could go to heaven only on the two solstitial days. Because, in order to 'change trains' comfortably, the constellations that serve as 'gates' to the Milky Way must 'stand' upon the 'earth', meaning that they must rise heliacally either at the equinoxes or at the solstices. The Galaxy is a very broad highway, but even so there must have been some bitter millenia when neither gate was directly available any longer, the one hanging in midair, the other having turned into a submarine entrance ...

June 10 was evidently an important date:

... The month, which takes its name from Juppiter the oak-god, begins on June 10th and ends of July 7th. Midway comes St. John's Day, June 24th, the day on which the oak-king was sacrificially burned alive. The Celtic year was divided into two halves with the second half beginning in July, apparently after a seven-day wake, or funeral feast, in the oak-king's honour ...

In the G text there could be traces of such ideas and there is indeed someone inside an oval in Ga1-16 where the dot in front attracts attention. The point of the Bull's upper horn (Elnath) seems to hoist Auriga across the Milky Way and at a later time Perseus would fly across and leave the Medusa head behind.