“If the work of Bosch is an island, it is like the water-surrounded town of Den Bosch itself,” Schwartz writes, using the shortened name of ’s-Hertogenbosch, “connected by bridges, roads and sea routes to more than one mainland.”

Departing from the realm of scholarship and art historical debate, the Dutch novelist Cees Nooteboom, invited to appear in a documentary to be broadcast in Bosch Year, uses the occasion to take a personal tour of Bosch paintings in various European museums. He is granted exceptional access to “The Garden of Earthly Delights” at the Prado, and follows up with trips to the Museum Boijmans Van Beuningen in Rotterdam and the Museum of Fine Arts in Ghent, among other locations of Bosch masterpieces.

The resulting slim volume of meandering, loosely philosophical observations is really an extended essay with five postscripts printed in a large font, illustrated with details of key paintings, in which he puzzles over Bosch’s imagery, in awe of the sheer originality and complexity. “Now that I am standing close to them, the abundance of details assaults me,” he writes. “I would need a year merely to see everything, let alone to penetrate within.”

Image Detail from “A Dark Premonition: Journeys to Hieronymus Bosch.” Credit... Museo Nacional del Prado, Madrid

Nooteboom maintains this awkward remove from the artworks throughout, and the book ends, after much traveling, viewing and musing, in a note of conciliatory defeat. He writes: “With a variation on a famous Dutch line of poetry, you might say, ‘Just look, you do not see what you see.’ And that is exactly what I saw in Lisbon, Madrid, Ghent and now here: all that I saw, and yet perhaps not.”

The Harvard professor Joseph Leo Koerner offers a more gratifying exegesis in his eloquent and rich exploration, “Bosch and Bruegel,” in which he compares Bosch to his Netherlandish successor Pieter Bruegel the Elder, writing that they both “captivate and overload our sense of sight, entangling the eye in anomalous objects, actors and activities, and ensnaring the mind’s eye in enigmas and seeming secrets that arouse but never satisfy interpretive curiosity.”

Based on Koerner’s A.W. Mellon Lectures in the Fine Arts at the National Gallery of Art in Washington, the series of talks seamlessly form a book of linked essays that discuss individual paintings with magnifying precision, while simultaneously advancing a broader theory on art in a Europe emerging from its dark ages.

Koerner proposes that Bosch created what he calls “enemy painting” and “teaches contempt for the world by showing the rest of humanity sinfully enthralled by the world and at the brink of judgment and damnation.” Bosch’s didacticism, he observes, evolves with Bruegel, who later in the 16th century presents a vision in which devilish characters roam free, but “no one is against man except man himself.” These observations bring Bosch’s work into relevance today, beyond the obvious promotions of the Bosch Year, and we begin to grasp why those little hybrid demons still feel so contemporary to us 500 years after they were created.