Luna

Luna is the divine embodiment of the Moon in Roman religion, the female counterpart of Sol the Sun, and the two together made up the cult of the heavenly lights that measured the Roman day and month. She was imagined driving a two-horse chariot, the biga, across the night sky, as Sol drove his four-horse team by day, and she was worshipped under titles such as Noctiluca, the night-shiner, whose shrine on the Palatine was said to be lit up through the night.

An old temple of Luna stood on the Aventine, traditionally ascribed to the regal period, marking her as one of the ancient deities of the city. Over time Luna was drawn together with the Greek Selene and with Diana in her lunar aspect, and later still with the composite goddesses of the mystery cults, so that by the imperial age she could stand as one face of a many-named celestial mother. At her simplest, though, she remained what her name says: the Moon itself, honoured beside the Sun as one of the two great lamps of the world.

Luna's standard portrait in Roman art borrows heavily from the Greek Selene: a crescent moon set like a diadem above the brow, a flowing veil billowing overhead like a canopy of night, and a torch or a pair of torches carried to mark her passage through the dark. She is frequently paired with Sol on the same monument, the two riding in opposite directions across a single relief or flanking a central scene, as on the tauroctony reliefs of the Mithraic mysteries, where Sol and Luna witness the bull-slaying from the upper corners of the composition as the fixed lights of the cosmic order. This visual partnership carried into the calendar itself: the Roman month (mensis) took its rhythm from the moon's phases long after the civil calendar had been reformed to follow the sun, and religious observance was still reckoned partly by lunar markers such as the Kalends, tied historically to the first sighting of the new moon.

Luna also inherited, through her identification with Selene, the Greek story of Endymion, the shepherd she loved and visited nightly as he slept an eternal sleep, a tale later poets folded freely into her Roman persona even though it has no native Latin origin. Her afterlife in language is perhaps her most lasting monument: lunar, lunacy and lunatic all descend from her name, preserving the old belief, never fully abandoned, that the changeable moon could unsettle the changeable mind. In astrology she remains the swiftest moving of the classical lights, completing her circuit of the zodiac in under a month and standing, opposite the Sun, for feeling, habit and the private self rather than for will and identity.