LONDON – His life was brutish and short, but Michelangelo Merisi (1571-1610), known as Caravaggio, changed painting. Like Giotto and Leonardo and Manet, he showed what had always been there but had never been made by human hand. From 1599 on, no one who had seen his work could paint without reference to it.

A more unlikely cultural titan it is hard to imagine. Caravaggio was a thug, given to violent quarrels and ceaseless posturing. All manner of crimes are attributed to him, though it is hard to separate fact from fiction – his first biographer was a painter who he had continually insulted and who returned the contempt. Caravaggio’s life and art stirred up strong passions. Every gross or obscene painting was attributed to his brush in the years after his death, every crime from murder to pederasty. He was famous for no more than 11 years, infamous for a generation, and then forgotten for 300 years.

His name resurfaced a century ago, but it was the Italian art historian Roberto Longhi’s landmark 1951 exhibition in Milan that re-established Caravaggio’s reputation. It has advanced unstoppably since. It is likely that more books have been written on him in the last decade than on any other artist except Picasso or Leonardo – and certainly more novels. He is newsworthy, too, as the canon of his paintings is not set. Scholars, curators, dealers, and amateurs live in hope of discovering a lost Caravaggio, as was the case with the “Taking of Christ,” found in 1994 in a Jesuit college in Dublin. This picture is a remarkable compression of the action on the Mount of Olives, but the question remains: Which of three versions (now in Rome, Ireland, and Odessa) is the autograph? Caravaggio’s influence on his contemporaries was such that there are innumerable copies of his works. A generation of painters used his brushstroke, imitated his composition of light and dark, and stole wholesale from his pictures. The hopes of curators and art dealers spring eternal.

These hopes are out in force at the season’s most important art exhibit: “Caravaggio: The Final Years.” In Naples from October 2004 to January 2005, it is now at London’s National Gallery. The Naples showing included a section of “new proposals.” I’ve only seen them in the catalog, but these are dubious pictures at best. The only possibility seems to be that the Carpineto Romano “Saint Francis” may be the autograph work, rather than the traditionally attributed one in Santa Maria della Concezione. (The seriousness of the Caravaggio business is clear from the fact that the Italian fiscal police have an ongoing investigation into five of these proposed Caravaggios.) For New Yorkers the sad news remains that though this show was conceived jointly with the Met, our hometown treasure house politely stepped aside when it became clear that it would be impossible to secure the major loans if there were a third venue. If you couldn’t go to Naples, you should consider an immediate trip to London before the exhibition closes.

The young Caravaggio took his talents to Rome, the capital of the artistic world, around 1590. He lived a vagabond’s life, but by the end of the decade had established himself as a painter of remarkable virtuosity with a penchant for impetuous, self-destructive acts. Despite attracting two powerful cardinals as patrons, Caravaggio lived on the cusp of disaster and fled Rome in 1606 when he killed another rough in a fight said to be about cheating at tennis. He spent his final four years in flight, first in the Colonna lands south of Rome, then in Naples, Malta, and Sicily. He worked constantly, and this period is the subject of the present show at the National Gallery.

It opens with the perfect comparison: two versions of “The Supper at Emmaus.” The first is the 1601 version from the National Gallery – seen last year at the Met in the “Painters of Reality” show – which is all about the astonished reaction of the two disciples realizing that the young, beardless figure is Jesus risen from the dead. It is a work of stark light and melodramatic gestures; a dish of fruit falls off the canvas into the viewer’s lap. The second version, done shortly after he fled Rome with a sentence of death over his head – one that the papal police could execute on sight – is somber. Jesus looks as we expect, and only the innkeeper seems to have recognized the risen son. Too much can be read into the pictures from biography, but they introduce the show splendidly.

Caravaggio’s work was a revolution in painting, a revolution that continued even in flight. His public debut in 1599, with three pictures of the life of Saint Matthew in the church of San Luigi dei Francesi, was one of the most astonishing announcements in the history of art, akin to “The Waste Land” or “Rite of Spring.” Here is the birth of the Baroque, a style to soon be spread by a host of imitators and advanced by a small number of masters: Rubens, the Caraccis, Orazio Gentileschi, Zurbaran. The innovative nature of these works cannot be overstated. Caravaggio painted fast and with little drawing or underpainting. He broke the plane of the canvas, so it seems as though the action were in three dimensions. He used harsh, thrust-stage lighting and obscured the traditional iconography of biblical narrative. Even the fact that they are giant canvases painted in studio and installed later was innovative.

Caravaggio is often said to be a “realist” painter, which is meant to demean him as coarse compared to Rubens or the Caraccis, with their more certain descent from High Renaissance and Netherlandish art. What he did, though, was to bring painting into the quotidian, using models in contemporary dress and painting biblical figures as recognizable Roman types. This can still be startling in Rome where pictures like the “Madonna di Loreto” in Sant’Agostino or the versions of Pauline Conversion and the martyrdom of Saint Peter in Santa Maria del Popolo hang in close proximity to the work of Raphael’s followers and the Mannerists. Caravaggio’s style continued to evolve after his flight: He began to compress the action of stories into tight, detailed canvases and developed a palette of colors that throb rather than impress with sensuousness, as the reds so often do in the Roman pictures.

There are only 16 paintings on view in London, but this is as large a group as one is likely to see gathered. It is an exhausting exhibit. The small galleries are illuminated in approximation of the dark, Italian churches that these works were painted for. The installation is successful – a rare chance to get up close to some of the pictures – but these quickly become overcrowded, dark rooms. The first struggle is to take in the gorgeous canvases and their drama – at times startling, at times embarrassingly juvenile as when, for the severed heads of John the Baptist or Goliath, he painted his own.

The intellectual struggle is to try to understand what these paintings say to each other and how they fit into the context of Caravaggio’s short life. Are the variations in color palette and composition intentional or driven by the paucity of materials available to a painter on the lam? Are the pictures fully finished works or a product of haste? When did he paint each picture – the hardest question of all? Was his constant use of self-portraits a sign of mania or a tongue-in-cheek slap at his patrons?

It is incredibly good to see the two Messina altarpieces, “The Raising of Lazarus” and “The Adoration of the Shepherds,” in conjunction with the Nancy “Annunciation.” The debate about whether the latter was done at the same moment as the Sicilian pictures will go on, but I found the idea sustainable. The size and composition of the last two is quite similar, as is the tone. To my eye, they are of a piece, though the condition of the three pictures is terrible and must confuse every attempt to settle their date and provenance. Seeing them together is the greatest success of this show.

The greatest mistake of the show is the hanging of the two versions of “Salome With the Head of Saint John the Baptist” side by side. The early one is obviously from his Roman period – with its vast swath of red cloth and open space – and has little in common with the late version, a taut, compressed picture. The latter work should have been hung with the exhibition’s last painting, “David With the Head of Goliath”: similar studies of a violent aftermath in washed-out color and tightly focused action. The extended arms of David and Saint John’s executioner are the true comparison.

There are certainly more pictures I’d have liked to have seen – works from Naples and Malta that simply cannot travel – but the exhibit depicts the full range of Caravaggio’s evolution as he sought for a pardon that would bring him back to the Papal States. The monochromatic “Saint Francis in Meditation” (1606) and “The Crucifixion of Saint Andrew” (1606-07) are at the extremes of the range of his religious works. The Naples “Flagellation” is as intimative of the violence of the Passion as any painting I have ever seen, and the delightful “Cupid Sleeping” with its wheezing fat figure is pure joyful bravado – perhaps painted as a tribute to the chastity vow of the Knights of Saint John. The Cupid’s wing stands straight up as he lies stretched out like a Titian Venus, but asleep and unaware.

The show is a marvel, but it can’t replace journeys to Naples, Malta, and Sicily. And the Caravaggio Trail will always begin in Rome, with his finest works scattered throughout the churches and the city’s best museums. The Vatican rejected his fabulous “Madonna of the Palafrenieri” – now in the Borghese Gallery, thanks to Scipione Borghese’s voracious appetite for art – but they kept his bold, larger than life size “Deposition.”

When you go to the Vatican Museums to see it, look carefully at Raphael’s final painting, his “Transfiguration.” If Raphael had lived, his direction is clear: toward the harsher lights and realistic oils that we think of as Caravaggio’s hallmarks. He is the mentor of the Baroque. Caravaggio knew the Raphael: His depiction of Lazarus reaching up at Christ’s call quotes from Raphael’s depiction of the curing of the epileptic boy – a figure itself inspired by Michelangelo’s ignudi on the ceiling of the Sistine Chapel – in the right foreground of Raphael’s last work. Here is one great painter pointing the way forward for another.

Until May 22 (Trafalgar Square, London, 011-44-207-020-7747-2885).