"North and south of the nebula Praesepe are two stars, which Orientalists speak of by a name evidently of some antiquity. Asellus means an Ass, and one was called Asellus Borealis, the northern Ass; while the other, Asellus Australis, is the southern Ass. The sign [for Cancer] was afterwards known by the symbol , which stands for these two asses."2 This glyph for Cancer is still used today.
A quick check of any star map confirms this. The star γ (gamma) is named Asellus Borealis, or 'northern donkey', and the star δ (delta) is named Asellus Australis, or 'southern donkey'.3
"Asellus borealis and Asellus australis, the Northern and the Southern Ass Colt, were the ’Όνοι, or Asses, of Ptolemy and the Greeks; the Aselli, or Asini, of the Latins, distinguished by their position as here given, even to the present day, and now popularly known as the Donkeys. ... and the Arabians similarly knew them as Al Himārain, the Two Asses."4
Hence as the Sun travels through the constellation of Cancer, it figuratively rides two asses, or an ass and colt, into the middle of summer. Of course everyone is happy to greet the arrival of summer. It's the best time of year, and the harvest is just around the corner.
Comparing this with our Jesus story, a high point of the Jesus story is Jesus' triumphal entry into Jerusalem, awkwardly riding both an ass and colt. "They brought the ass and the colt and put their garments upon them, and he sat on them. (Matthew 21:7) We have here Jesus riding on both an ass and a colt. Quite a trick if interpreted literally, but in astronomical allegorical terms it's simply what happens.
19. The Sun figuratively rides an ass and foal into the middle of summer.
Jesus rides an ass and colt into Jerusalem.