In the understanding of medieval alchemists, the Sun and Moon, like Mercury, Venus, Jupiter, Mars, and Saturn, were all planets revolving around the Earth. They were represented by the seven metals of gold, silver, mercury, copper, tin, iron, and lead respectively. But this was not absolute; it also depended on the alchemist's coded language and the context at the time.
Gold was regarded as a perfect metal, while mercury could dissolve it. Mercury usually represented Hermes, the god of alchemy, which gave rise to an idea in "Hermetic alchemy": dissolution and coagulation were two opposing forces within it. The Muggle chemistry Arif mentioned was the "external Virgo." This constellation occupied the sixth position of the zodiac, while the other side of the collective unconscious was the "internal Pisces," the twelfth constellation of the zodiac.
Of course, Hermetic alchemy was not the only kind in this world. But nearly everyone at the conference today was a "Hermetic philosopher," apart from Pomona, an oddity with some knowledge of Herbology alchemy.
The purpose of the Philosopher's Stone was not to create gold. That was merely a step in the process. A true Hermetic philosopher's ideal should have risen far above the material realm, though for a long time, many alchemists had abandoned research into the inner world and focused instead on discoveries in the "external world," obsessing over mixtures and compounds.
Virgo possessed a trait that pursued perfection, and gold was a perfect metal. Pisces, meanwhile, loved to dream; there were many worldly matters that Pisces simply could not be bothered with.
Of course, some would say astrological Divination was damned superstition. As the "external world" developed at an accelerating pace, research into the inner mind was suppressed, surviving only in the form of "superstition, fantasy, and daydreams."
But things began to change