In an alternate version of the sixteenth century the world is flat, its outer edges still unexplored. An ambitious alchemist, a boundary-pushing doctor and his daughter, a ship-load of Protestant refugees, and some stowaway mythical creatures set sail for the legendary island of Horizon on the outer rim of the earth. Some are looking for treasure, others for religious freedom, and still others for immortality. They are pursued by a Roman Catholic inquisitor (persecutor) and representatives from the British crown who want to ensure the treasure returns to England.
Overall, the story is well-written and fascinating. The strange and (seemingly) magical creatures the reader encounters on the island of Horizon are wonderfully imaginative, and Walton does a good job weaving them into the plot development. Ultimately there is a scientific explanation for everything that the main characters slowly uncover through trial and error, sometimes with disastrous effect. There were only two fantastical elements that blatantly ripped-off scenes from The Voyage of the Dawn Treader: ocean water that turns from salty to fresh as the ship approaches the edge of the world; a magical pool that turns to gold anything that gets dipped into it. (Perhaps these ideas are older than Lewis’ versions.) Otherwise, the fantastical world was very original, including the explanation.
My biggest problem with the book is that the setting is the 1500s but the voice of the characters and the narrator is distinctly modern, which makes the overall tone sound a bit juvenile and unserious. Walton genuinely interacts with a lot of weighty issues through the development of his characters: Protestantism and Catholicism, atheism and belief, classic feminism (as in basic equality, not the Feminazism we see today) in a patriarchal society, the meaning of death and afterlife, humanity and souls, parental relationships, and marriage. But the tone and style just seemed anachronistic to me.
Quintessence is a fun read that combines serious philosophical issues with fast-paced adventure.