Masterpiece: Isenheim Altarpiece: Grünewald's Towering Biblical Tableaux
Among the most affecting artworks ever created, painter Matthias Grünewald's 16th-century polyptych is an awesome, unfolding journey through places hellish and paradisiacal

The Musée Unterlinden in Colmar, near the German border in northeastern France, sits at the end of many an art pilgrimage to a spectacular work: the Isenheim Altarpiece (1512-16) by Matthias Grünewald. This intense, imaginative polyptych—lauded by innumerable textbooks—ranks high among the most affecting artworks in all of art history. Alternately shocking and pleasing the eye, it has influenced generations of artists, including Picasso, Matisse, Otto Dix and Jasper Johns.

Grünewald (c. 1470-1528) created this imposing work for a monastery hospital dedicated to St. Anthony the Abbott, whose help is invoked for relief from skin diseases (especially "St. Anthony's Fire," which is characterized by burning pain, gangrene and, sometimes, hallucinations). Stretching about 15 feet at its widest, it consists of a series of central panels and wings that unfold to reveal religious tableaux, from the hellish to the paradisiacal. Last year, Grünewald's brilliance became even more apparent after a 4 1/2-year restoration was completed. Now his colors, always striking, are more vibrant and more varied; his touching details, like a tear on Mary's face, are more visible; his aspiration to inspire hope in and comfort from Jesus, who likewise suffered, is more evident.

So that all pieces can be seen—in its day, the liturgical calendar determined which panels were visible—the altarpiece has been partially disassembled. Visitors entering its nave-like gallery first see the most famous view, of the Crucifixion. It's a gruesome scene, with Christ's lacerated body in a tattered loincloth, visibly wracked by pain and discolored by death, his claw-like fingers and curled toes stiffened by rigor mortis. Blood, now congealed, seeps from his side wound. Below Christ—intentionally larger than the figures attending him—a pale, fainting Mary in stark (and unusual) white garments is held up by St. John the Evangelist in red; a prayerful, kneeling Mary Magdalene gazes up at Jesus, her curved body aligned with Mary's; and St. John the Baptist, also in red, stands beside a wounded Lamb of God whose blood drips into a chalice, symbolizing the Eucharist.

The Baptist actually died before the Crucifixion, but Grünewald includes him to explicitly confirm the New Testament creed. As the Unterlinden's former director, Pantxika de Paepe, writes in her 2016 book, John represents the Old Testament, where his birth is prophesied. Here he points his finger at Jesus, calling attention to an inscription in red behind his outstretched arm: "He must increase, but I must decrease."

Grünewald's novel color scheme ties the scene together, as do strong parallel diagonals linking Mary's posture with Magdalene's and the lamb's; John's finger with Christ's right arm and the dark, sloped background landscape; and even some lines in the predella, which presents a horrifying lamentation, and in the side wings, which depict St. Sebastian, who was martyred with arrows, and a full-bearded St. Anthony. Notably, above St. Anthony Grünewald painted a horned devil in a leaded window whose eyes fix on the viewer.

Fortunately, the mood lightens in the following panels. Grünewald's "Annunciation" is a delight. A young Mary, her cheeks now full of color, is interrupted during her Scripture reading in a Gothic church. Although she shyly turns her face away from the angel Gabriel, whose billowing robes swirl around him, her half-closed eyes meet his; above them hovers a haloed, barely visible dove of the Holy Spirit. In "Virgin and Child," Mary sweetly cradles Jesus's head in her hand; he plays with coral beads, which have multiple meanings in Christian iconography, including the foreshadowing of his passion and death. Grünewald again deploys subtle eye contact, here to signal joyful intimacy between Mary and her son.

At first glance, Grünewald's triumphant "Resurrection" might seem unfinished. Christ's now nearly perfect body, so light in color and so aglow, appears unreal: Grünewald has painted what cannot be seen by man, Jesus as the divine. Ingeniously, the scene flashes back to the Transfiguration, where a radiant Jesus appeared to three apostles, and forward to his Ascension. Grünewald conveys the Resurrection's turbulence, however, with his depiction of the fearful soldiers, tumbling away from the grave they were sent to guard.

Of the other panels, the seemingly beatific "Concert of Angels" centers on a blond, pink-clad angel playing a viola da gamba before an ornate, gilded canopy housing other musicians and singers. Surprisingly, Grünewald interjects evil—or mystery—by inserting a stone-faced greenish creature, also playing a bowed instrument. It may be Lucifer.

The final panels picture episodes in the life of St. Anthony: a conventional "St. Anthony Visiting St. Paul the Hermit" and an utterly inventive "St. Anthony Tormented by Demons." Here, Grünewald lets his imagination run wild, depicting St. Anthony pinned to the ground, surrounded by scary demons and ugly monsters equal to, or more haunting than, anything concocted by Hieronymus Bosch (or Hollywood). While one pulls his hair, a giant bird raises a club at him and other creatures rush to stomp on him. Again, Grünewald lets hospital patients know they are not alone.

Those two paintings border gilded sculptures by Niclaus of Haguenau (c. 1445/1460-before 1538) of St. Anthony, St. Augustine and St. Jerome at the altarpiece's core. Created before Grunewald's painting, it's a solid work, but, comparatively, nothing special.

Grünewald's superior artistry seems endless—with incredible depth of field, expressive faces, realistic details, iconographic symbols, a sense of moment and rhythm, and so on. It's no wonder that many visitors often sit and stare at Grünewald's towering achievement for hours, leaving both awed and shaken.