And then there are the amazing paintings themselves: the slightly dazed homoerotic evocations of a young John the Baptist snuggling with a horny old ram, the debauched child-god Bacchus, the seductive lute player. In a very different key, dramatically staged and lighted, are the "you are there" biblical scenes: St. Matthew summoned from his countinghouse to a different life. "Who, me?" he seems to say. Or St. Paul lying dazed on his back on the road to Damascus, his horse looming dangerously above him. "His raised hoof won't crush his thrown rider," Prose writes, "not even if he has to hold it like that for a lifetime."

Prose's Caravaggio is an artist of intensity and transgression, requiring in both art and life an almost violent sense of the real: "Matthew's rough meat hook of a hand" or the shockingly "bloated corpse" of the dead Madonna. Prose, whose "Lives of the Muses" convincingly explored moments of reinvention in the lives of male artists inspired by women, is particularly good on the nature of conversion, both in the paintings of Matthew and Paul and in the artist himself, for whom each painting represented "a frozen glimpse of forever" amid "the terror of revelation."

As an art critic, Prose is a bit of a street brawler herself. She swaggers among her rivals like Mercutio, spoiling for a fight. Contemplating Caravaggio's bizarre, queasy self-portrait as "Sick Bacchus," Prose claims that "few critics have bothered to point out the obvious: how deeply strange the painting is." But she has learned a lot from those few, and one wishes she were a little more gracious to the art historians who bolster her arguments. She chides the naïveté of "many of these academic and literary conversations" about Caravaggio's sexual proclivities, but when she says, quite accurately, that "sex between men in Caravaggio's time was viewed very differently than it is today," those academic conversations are why she knows this.

Nonetheless, Prose brings to Caravaggio a fresh and unflinching eye. Her pages on his final months -- as he flees across Italy to Naples and then, astonishingly, to Malta, pursued by a partly phantasmal posse of papal guards, Maltese knights and Roman street toughs -- have some of the intensity of Caravaggio's own claustrophobic final works set in "dark crypts and bleak rooms." An early biographer's words on Caravaggio's last journey could serve as the painter's epitaph: "Bad luck did not abandon him." Or, as Prose handsomely sums it up: "Having spent his brief, tragic and turbulent life painting miracles, he managed, in the process, to create one -- the miracle of art, the miracle of the way in which some paint, a few brushes, a square of canvas, together with that most essential ingredient, genius, can produce something stronger than time and age, more powerful than death.

Christopher Benfey teaches English at Mount Holyoke and is the author of "Degas in New Orleans" and "The Great Wave."