The Sun’s and the Moon’s paths are essentially the same in the same direction: the Sun’s route is the ecliptic, as previously noted, while the Moon is inclined at approximately 5 degrees to the ecliptic. The Moon’s crossing of the ecliptic from South to North symbolises an ascent and its crossing of the ecliptic from North to South symbolises a descent. The Moon’s crossing points of the ecliptic, the ascending node (ὁ ἀναβιβάζων σύνδεσμος) and the descending node (ὁ καταβιβάζων σύνδεσμος), are also related to the lunar nodes depicted as the Mithraic torchbearers with raised and lowered torches in the tauroctony (De Antro 24.13-25.1). As Beck rightly observes, the Sun’s rays has a function of apogenetic power, and its characteristics such as superior, high/up, heat/fiery, male are compatible with the ascending path of the soul, whereas the Moon asthe nearest to the Earth is inferior, down/low, cold/eartly, female.
Porphyry’s primary concern about the association of the gates of the Sun and the Moon with the two celestial openings of Plato in Republic 10 is ethical, rather than suggesting simply an astrological interpretation. The ascending path towards the Sun can be compared to the escape of the liberated prisoner from the Platonic cave, representing a choice towards a philosophical life instead of slavery to the material world. The path through the Sun symbolises the bright side of the soul under the guidance of its rational part, as is the case with the diurnal houses of the seven planets; similarly, the path through the Moon can be considered to be a symbol of the dark side of the soul under the guidance of its irrational part, as is the case with the nocturnal houses of the seven planets.
Akçay, K.N., 2019, Porphyry's On the Cave of the Nymphs in its Intellectual Context. Leiden/ Boston: Brill.