If medieval monster imagery seems surprisingly nuanced at times, it’s at least partly because image-making was a slow, careful process that left the artist with plenty of time to think through the meanings of his work. For most of the thousand years between the fall of the Roman Empire in the 5th century and the dawn of the Age of Discovery in the 15th century (the two events that are usually thought to bookend the medieval era), war and disease set back Europe’s trade with the rest of the world, making pigments considerably rarer. Some, like red ochre, could be made from the clay found almost anywhere, but others, like ultramarine, had to be transported to Europe from the Middle East at a huge cost. Producing a tiny illustrated copy of the Book of Hours, one of the most popular Christian devotional texts of medieval times, required thousands of miles of travel, not to mention hundreds of hours of eye-straining labor—and all that just to paint the Virgin Mary’s luminous blue robe.

Examining one of the illustrations from a 15th-century Belgian copy of the Book of Hours, you can see how much love and care medieval artists put into their monsters. The scene—one of the most iconic in Christianity—shows Saint George a split second before chopping the head off of a dragon. To 21st-century eyes, George’s heroism might seem a tad comical—the dragon isn’t much bigger than a golden retriever, and it appears to be sitting belly-up, revealing a set of yellowish genitals. Yet the artist’s eye for detail stuns more than 500 years later: You can still make out the scales on the monster’s tail and the gleam in its beady eyes. Not for the first or the last time in art, the villain makes the hero look almost bland by comparison and threatens to run away with the whole show.

Not all medieval monsters were so charismatic, however; in fact, one can’t understand medieval-era images of monsters fully without understanding the ugliness and sheer, stupid meanness that inspired many of them. Anti-Semitism—which could plausibly be defined as the representation of Jews as monsters—was indisputably central to European culture of the era; bloodthirsty Jewish ogres served as stock characters in countless plays, stories, and poems. In one of the most popular genres of medieval fiction, a young, pious child would be murdered savagely, usually by a Jew, and then resurrected, with the Jew receiving an equally savage punishment (which the Christian audience would be encouraged to gloat over).