How Renaissance Rome got real

Fancy dressing up as a trickster from a famous late 16th-century painting? This week, should you happen to have £395 to spare, you could become the proud owner of a gorgeous waistcoat designed by Tom Gilbey (silk brocades, fine wool, hand-embroidered), created in imitation of one worn by the young cardsharp in Caravaggio's great painting of the same name, currently hanging in the Royal Academy's celebration of the birth of the Baroque.

Fancy dressing up as a trickster from a famous late 16th-century painting? This week, should you happen to have £395 to spare, you could become the proud owner of a gorgeous waistcoat designed by Tom Gilbey (silk brocades, fine wool, hand-embroidered), created in imitation of one worn by the young cardsharp in Caravaggio's great painting of the same name, currently hanging in the Royal Academy's celebration of the birth of the Baroque.

And, as a magnificent complement to that waistcoat, you could also purchase a velvet headpiece complete with feather (also from that painting, though the colours are, alas, unfaithful) by Pip Hesketh (£1,500 - ouch!), together with a selection of Andrew Logan's jewellery: a spot pin, a mandolin pin or a cue-pid (sic) brooch. Depending upon which way you incline (to much Caravaggesque personal adornment or little), and how deep your pocket is, the jewellery could set you back between £200 and £400 per item.

Should you feel in the mood to walk around disguised as any other of the characters in this exhibition of approximately 140 paintings executed in Rome between 1592 and 1623 - the Virgin Mary, perhaps, Hercules, or one of the succulent nymphs of Diana, that execrable traitor Judas Iscariot, or even the bloody head of Holofernes - you will have to organise the commission yourself, because the Royal Academy's cabinets offer only items purloined from Caravaggio.

And this, in short, is the difficulty and the triumph of this huge show. Caravaggio so eclipses everyone else that you find yourself hurrying from room to room in pursuit of the few that are here, the best of which are in Galleries One, Two, Six, Seven and Eight - nine great paintings in all.

The first significant early works are in Gallery One, whose general theme is the growth of still-life and genre painting during these years. Caravaggio first arrived in Rome from Lombardy in 1592, a young man of 21, and at first he lived in the house of a priest who was so niggardly that he fed the painter on nothing but lettuce. Caravaggio found work as an apprentice to the celebrated painter Cavaliere d'Arpino (much represented in this show), who set him to painting fruit and vegetables, a lowly task fit for a northerner such as Caravaggio. Caravaggio bridled - he had more elevated ambitions for himself as a history painter - but he did it all the same, and the fruits of his labours can be seen in Young Boy Peeling Fruit and Boy with a Basket of Fruit.

In the first, a boy is seated at a table, peeling a citrus fruit; in the second, a young street vendor appears to be offering a basket of fruit to the onlooker. In both paintings the fruit has a luscious, tactile, uncommonly realistic quality. The street vendor, tousle-headed, full lips parted, radiantly provocative in his pose, appears to be offering himself as readily as he is offering his fruit. The film-maker Derek Jarman thought he understood exactly what all this meant - and he may have been right. Though Caravaggio never became known as a painter of still-life, his example in these paintings was nonetheless enormously influential in the creation of still-life as a separate genre of painting.

Across the room from the street vendor hangs one of Caravaggio's most famous early works, The Cardsharps, painted in the mid-1590s. A fashionable young man is being gulled by two cardsharps. One, the raffishly dressed, wild-eyed elder, looks over the boy's shoulder and indicates to his fellow trickster the card that the innocent is holding. We see the young trickster - he of the brocaded waistcoat and the feathered hat - reach behind his back for the card which is tucked into his belt. Caravaggio used the same model for the young gull as for the cheat, pointing a moral. This painting of a rake's progress became enormously popular with other painters. It was repeatedly imitated - some of the less good imitations are in this room - and it helped to create an appetite for low-life genre scenes. All these early works testify to the presence of a great and turbulent talent.

The defining features of all his major works are already clearly present in these early canvases: the dramatic use of raking shadow; the curiously indefinite backgrounds; the explosively naturalistic rendering of people; the favouring of the real at the expense of the idealised and the classical; the almost stagily direct appeal to the onlooker. In short, the sheer human empathy that his paintings provoke.

But Caravaggio was only a part of the story of the growth of the Baroque. The artistic renaissance in Rome at the turn of the 16th century happened because of the power of patronage that was wielded by the Catholic church. Pope Clement VIII (1592-1605) saw the imminent arrival of the new century as an opportunity to celebrate the onward march of Catholic Christendom. Palaces were refurbished; new churches were built; and ecclesiastical paintings were being commissioned by the score. Painters began to flood into Rome from all over Europe in eager pursuit of lucrative commissions.

One of the painters summoned to Rome in those years was Annibale Carracci. Carracci arrived in Rome in 1594 from his native Bologna at the request of Cardinal Farnese. Carracci represented a tendency that was diametrically opposed to that of Caravaggio, and one, moreover, that would be much more influential in the growth of Baroque - think of Bernini, for example. He believed in the Classical tradition and the Classical ideal - and what better place to celebrate it than the great Classical city of Rome itself? The Classical ideal meant much more than an interest in Classical antiquity, though that was a part of it. It meant, in essence, that human life in the raw, the undifferentiated street life which so fascinated Caravaggio, was not enough. Don't be unselective, argued the Classicising tendency. Only the best is good enough for humankind. Man's sights have to be raised, not lowered. (This great theme was to be taken up a little later by the great Baroque art theorist Giovanni Battista Agucchi, whose arresting and spirited portrait hangs in Gallery Four.)

Carracci's Hercules at the Crossroads shows his rather lumpish Classicism in action. Painted for the ceiling of the camerino of the Farnese Palace, a building which is now almost inaccessible to art lovers because it serves as the French Embassy, it shows Hercules being offered two choices, one by Virtue, the other by Vice. Vice, a graceful young woman, wispily clad, could scarcely look more appealing. Vice directs him up a stony, rocky path, at the top of which stands a horse - an emblem of the Farnese family, his current employer. A poet crouches in the left-hand corner, time-servingly recording the fact that Hercules is making the correct choice. How dreary and moralistic it all seems!

The last room of all contains a selection of important altar pieces, often commissioned for churches built by one or another of the newly-founded Catholic Orders - the Jesuits, the Oratorians, the Theatines - and all hung at the height at which you would expect to see them when in situ: high. These are the kinds of works that every artist of this time would have aspired to paint, such was their size, their importance and their prestige. Here are the two different attempts Rubens made to please a difficult patron; Federico Barocci's lovely altarpiece of 1608 in celebration of the Eucharist - a rich night scene with the most exquisitely soft coloration - executed for the Basilica of Santa Maria sopra Minerva (which stands next to the Pantheon), and, best of all, the most famous pair of outrageously filthy feet that have ever been painted in the history of Christendom.

Caravaggio's Madonna di Loreto, painted between 1604 and 1606, shows two pilgrims kneeling at the feet of the Virgin. They have just made the arduous journey from Rome to the Adriatic Coast - on foot. And, understandably enough, those feet are filthy. And, thrust as they are into our faces, they completely dominate the painting. Outrageous, of course, in the context of such an otherwise perfectly orthodox painting.

Caravaggio, it seems, just couldn't stop being himself.

The Genius of Rome, Royal Academy, Piccadilly, London to 16 April. The exhibition is sponsored by Credit Suisse First Boston