I teach a course called “Harry Potter and the Middle Ages.” It’s an approach to medieval culture that takes the Harry Potter books as a starting point; we learn about the medieval background to many of the elements JK Rowling used to construct the Harry Potter universe. The course is organized around the Hogwarts curriculum. For example, in conjunction with Care of Magical Creatures, we study medieval bestiaries and medieval map-making (both Fantastic Beasts AND where to find them). Transfiguration and Potions classes offer the opportunity to learn about medieval alchemy.
Alchemy is clearly an important theme in the Harry Potter books, starting with the title and plot of the first book, Harry Potter and the Philosopher’s Stone. 1 It does not appear to be one of the courses offered at Hogwarts, however; perhaps Rowling wanted to save it for her underlying structure. In any case, learning more about alchemy enhances our understanding of both the Harry Potter books and of the Middle Ages.
The more I read about alchemy, the more I realized that mercury is a key substance in the alchemical worldview. Many medieval and early-modern alchemists hypothesized that the starting point for generating the Philosopher’s Stone was to mix mercury and sulfur (which may or may not refer to the physical substances that go by those names); this is known as the Mercury-Sulfur principle. I also realized that the meaning of Mercury is multivalent, with multiple connections to multiple things. Let’s trace some of those connections. The words in bold face are shown on the accompanying diagram.
Mercury was a Roman god, the Roman counterpart to the Greek messenger god Hermes. In late antiquity, Hermes also became identified with Hermes Trismegistus, or “thrice-blessed Hermes,” a figure to whom many early alchemical writings were attributed, known collectively as the Hermetic corpus and which were influenced by Neo-Platonist thought. This Hermetic tradition is evident in the term used by medieval alchemists to describe what they did to keep air out of a piece of equipment, a term we still use—“hermetically sealed.”
In addition to being the name of a god, Mercury is also the name of a planet. Ancient and medieval astrologers believed that the stars and planets influenced life on earth. Which planet a person was born under influences that person’s personality. Someone born under the influence of Jupiter might grow up to be jovial (jolly), while Saturn’s influence would make you saturnine (gloomy). The influence of Mercury, the fastest-moving planet, results in a personality that is mercurial (quick to change).
In ancient cosmology, each of the seven planets was associated with one of the seven metals. (“Planet,” from the Greek for “wanderer,” was the term for any heavenly body that “wandered” in relation to the fixed stars that form the constellations, which stay put. So the Sun and Moon were considered planets, but the stationary Earth was not.) Some of the associations are obvious—gold goes with the sun, silver with the moon. Mars is associated with iron, both because of the planet’s rusty-red color and because the god of war would have used iron weapons. Venus is copper, which in the ancient Mediterranean came from the island of Cyprus, where Venus was born from the sea.2 Saturn is lead, the heaviest of metals for the slowest of the planets. Jupiter gets tin because that’s what’s left over, and the planet Mercury, the fastest-moving planet associated with the god with winged feet, gets the slippery-slidy metal Mercury.
With one exception, we no longer use these associations. But alchemical texts might speak of combining Jupiter and Mars when they mean tin and iron. The only one of the metals that still retains its planetary name in common use is Mercury. There is, however, also a name that refers to the metal only—quicksilver. “Quick” here means “living,” rather than “speedy”; think of cutting your nails to the quick. So “quicksilver” is “living silver.” The Greek name for the metal is “hydroargyrum,” or “liquid silver.” This is the source of the modern chemical abbreviation for mercury (or quicksilver)—Hg.
So what does all this have to do with Harry Potter? Well, which character has a name that’s a form of the god/planet/metal we’ve been talking about? That’s right, Hermione (a feminine form of Hermes). And what’s her last name? Granger. So what does that make her initials? HG. And what do her parents do? They’re dentists. What do dentists traditionally make fillings out of? Mercury. Coincidence? I think not.
For further reading:
Lawrence M. Principe. The Secrets of Alchemy. Chicago and London: University of Chicago Press, 2013.