“This painting by Hieronymus Bosch satirizes a medieval surgical procedure, revealing a world where folly and deception often masquerade as wisdom. Look closely at the bizarre details, like the surgeon's hat and the 'stone' he extracts.”
In this unsettling scene, a surgeon, wearing a curious funnel-shaped hat, attempts to remove the "stone of madness" from a patient's head. The procedure, known as trepanation, was a real practice, but here, Bosch plays on the Dutch word "kei," meaning both "stone" and "bulb." The "stone" extracted is actually a flower bulb, suggesting a charlatan at work. A monk stands by, holding a tankard, perhaps offering comfort or complicity, while a woman with a book balanced precariously on her head observes the bizarre operation. This detail might satirize the custom of wearing book amulets or simply symbolize folly. The painting, an oil on panel from around 1494, immerses us in a rural landscape, with a distant town and gallows visible, hinting at a world where reason often battles absurdity.
- Artist
- Hieronymus Bosch
- Date
- 1503
- Location
- Museo del Prado
What to Notice
Five details hide in plain sight. Here’s where to look.

The surgeon’s funnel hat, a symbol of foolishness or trickery.
The flower bulb being extracted, instead of a stone.
The woman with a book balanced on her head.
The monk holding a tankard, observing the scene.
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Hieronymus Bosch
1450–1516 · Northern Low CountriesHieronymus Bosch, a Dutch painter from the Northern Low Countries, filled his oak panels with fantastic illustrations of religious concepts, from the Garden of Eden to macabre depictions of hell.
Further Works by Bosch
The Garden of Paradise
1495 · Art Institute of Chicago
The Conjurer (The Juggler)
1502
The Adoration of the Magi
Noordbrabants Museum
The Epiphany
1494 · Museo del Prado
The Mass of Saint Gregory
1494 · Museo del Prado
The Seven Deadly Sins and the Four Last Things
1500 · Museo del Prado
The Temptations of Saint Anthony
1501 · Museo del Prado
Paradise and Hell
1513 · Museo del Prado
More from Northern Renaissance
More works to explore
Beyond Bosch and Northern Renaissance: works from the same years.
Same era · 1480s–1510s
Mona Lisa
Leonardo da Vinci · 1503 · Department of Paintings of the Louvre
Same era · 1480s–1510s
Jacopo Pesaro, Bishop of Paphos, being presented by Pope Alexander VI to Saint Peter
Titian · 1504 · Royal Museum of Fine Arts Antwerp
Same era · 1480s–1510s
Drunkenness of Noah
Michelangelo · 1509 · Sistine Chapel
Same era · 1480s–1510s
Sistine Madonna (Madonna di San Sisto)
Raphael (Raffaello Sanzio da Urbino) · 1512
Same era · 1480s–1510s
Erasmus of Rotterdam
Albrecht Dürer · 1501 · Icones Leidenses
Same era · 1480s–1510s
Plate with arms of the Tosinghi family
Artist Unknown - The Mercat Cross, Aberdeen · 1495 · The Metropolitan Museum of Art
Same era · 1480s–1510s
Madonna and Child Enthroned with Saints John the Baptist and Sebastian
Pietro Perugino · 1493 · Uffizi Gallery
Same era · 1480s–1510s
The Archangel Michael
Master of the View of Saint Gudula · 1495 · The Metropolitan Museum of Art


