John Crowley’s Aegypt Quartet asks the question, “What if there was more than one history of the world?”; David Walton’s Quintessence, on the other hand, actually explores one of these alternate histories. It is set in a world that follows the rules of known science in the sixteenth century–which means the world is flat and alchemy is possible.

Lord Chelsey arrives from a voyage to the edge of the world on board the Western Star, but his arrival in London is unlike any undergone during the Age of Exploration. His entire crew is dead before they dock and the diamonds, gold, and silver that they brought from the distant continent of Horizon has turned to salt and sand.

Christopher Sinclair wants to find out why. A world explorer with enlightened views of science in a scholastic society that still reveres Aristotle as the final authority of knowledge, he has his eyes set on Horizon, a continent literally situated at the end of the world. In Protestant England he is feared as a sorcerer and a heretic, but he is really an alchemist who employs the empirical methodology of Sir Francis Bacon decades before the founding of the Royal Society.

Stephen Parris, a surgical doctor, is similarly beset by a European culture that misunderstands his work. Cutting corpses open to see how the human body works is considered a desecration of the sacred, but it is what obsesses Parris: the chance to see how illnesses work and find a way to cure them. Both Parris and Sinclair are united in their quest to conquer death using science, but they are at cross-purposes until the Spanish-led Catholics coup the Protestant kingdom and an inquisition descends on them both.

Soon Parris, Sinclair, and Catherine, Parris’ adventurous daughter who is eager for science as well and has made the acquaintance of a mysterious manticore, are off on an epic ocean voyage to discover the remains of Lord Chelsey’s colony. Sinclair leads the desperate crew onward with the promises of wealth and riches, but he really has eyes for only one thing: to discover the secrets of quintessence, the fifth element than binds earth, air, fire, and water.

Quintessence may be called the quintessential historical fantasy, situated as it is at the historical moment where what we consider fantasy is about to give way to rigorous science, as superstition slowly becomes erudition at the end of sixteenth century. Only in this alternate history, the fantasy stays through the dawn of science.

What is truly original about Walton’s historical fantasy, more than the idea of alchemy being real, is his combination of the ideas of quintessence and Darwinism in his explanation of the evolution of magical Horizon creatures. From the leviathan in the great ocean to the iron fish that can transform at will into heavy metal to the memory-sharing manticores, all the creatures on Horizon use quintessence to hunt or protect themselves from hunters in a science-magical ecosystem. Slowly the settlers learn from these creatures’ physiognomies in order to develop new kinds of technology.

Quintessence is a unique mix of historical fantasy that never forgets its historical situation, even if it might introduce Darwinism in all but name, along with other modern ideas–that’s the game of alternate history, after all. It is also unique in being equally a science fantasy. Finally, it’s a fun comment on some tropes of sixteenth century colonization and exploration, such as the voyages of Christopher Columbus, John Cabot, Sir Humphrey Davies, Sir Walter Raleigh, and Ferdinand Magellan, who were each either lost at sea, brought worthless metals home thinking they were gold and diamonds, founded failed colonies, converted the natives, or made Europeans aware of the true size of the globe.