Two Gates of the System
(early prototypes)

This is an 18th-century alchemical medallion

The obverse shows a monogram of the alchemical symbols for Sulphur, Salt, and Mercury, crowned by the Sun (Philosophical Gold) and the motto “Trinum in Uno” (“Three in One”), referring to the perfect union of the three principles in the Philosopher’s Stone.
The reverse depicts Saturn/Kronos with his scythe, wooden leg, and wings, leading a bound, “fixed” Mercury. Above them shine the Sun and innoscriptions “Tandem”, “Per Me”, “Sine Me Nihil”, “Si Voluero”, forming an allegory of Mercury’s transformation in the Great Work. The innoscription around the edge refers to Mercury’s dual, unifying nature — the substance that joins Sun and Moon.