The figure is not a goat but a goat-fish, a creature with the forequarters of a goat and the tail of a fish, and it is one of the most durable images to come out of Mesopotamia, where MUL SUHUR-MASH, the goat-fish, is associated with Enki-Ea, the god of the sweet waters under the earth and of craft and wisdom. The Greek tradition explained the composite shape with a story of Pan leaping into the Nile to escape the monster Typhon and transforming only partly. The hybrid form, half creature of the heights and half creature of the depths, was read by later commentators as an image of the soul's double nature. In the Neoplatonic scheme of Macrobius the winter solstice in Capricorn is the Gate of the Gods, through which souls ascend, the counterpart of the summer gate in Cancer.
The goat-fish figure appears already fully formed on Babylonian kudurru boundary stones and cylinder seals many centuries before the Hellenistic zodiac reached its standard twelve-sign form, making it one of the longest continuously attested single symbols in the whole system; the Enki-Ea association reflects that god's residence in the Abzu, the cosmic freshwater ocean beneath the earth, which the fish-tail half of the figure directly pictures. Some later Hellenistic astrologers, working from a folk etymology rather than any documented Babylonian source, connected the goat-fish to Pan's escape from Typhon by way of the Greek word for horn, a derivation modern philology does not support but which nonetheless became the standard mythographic explanation repeated across Roman and later sources.