Sculpture lovely to look at, and thought-provoking, too

Would you like to see a miracle? I'm talking about a 1-foot square slab of marble whose surface has been transformed into a vision of the Virgin Mary seated in the clouds with her infant son in her lap and cherubic angels in fluttering attendance. It's carved in low relief with breathtaking delicacy, and it looks as though the stone had melted away, leaving only this dreamy, uncannily luminous mirage.

Made between 1425 and 1435 by Donatello, who was, next to Michelangelo, the greatest sculptor of the Italian Renaissance, "Madonna of the Clouds" welcomes visitors right at the start of "Donatello to Giambologna: Italian Renaissance Sculpture at the Museum of Fine Arts, Boston," an excellent, medium-size exhibition.

For the show, curators dusted off and gathered together almost every piece of Italian Renaissance sculpture the museum owns, including works in stone, bronze, wood, and clay. It also borrowed some items from the Isabella Stewart Gardner Museum and, from a private collection, a fascinating array of tabletop-scale bronzes.

Organized by MFA curator Marietta Cambareri , it's not a blockbuster -- there are no big-time masterpieces by household names, and there are lots of minor works, some of which are suspected of being fakes. Nevertheless, the show is loaded with lovely objects, and it serves as a surprisingly thought-provoking window onto one of the great transformative periods in the history of Western civilization.

For years scholars have debated how exactly the Renaissance should be defined and dated -- usually the 14th through the 16th century -- and how to describe its meaning and consequences. Lacking a catalog , the MFA show does not venture any new theories, but it does make vividly immediate some of the themes traditionally identified with the period: the revival of Greek and Roman classical idealism; the emergence of humanism and individualism; the shift from symbolism to realism.

These trends converge in the sculptural representation of the human body. Unlike the flat, stiff, semi-abstract figures of medieval art, Renaissance bodies look natural and, quite often, sexy. One of the most prized works in the show is approximately a two-thirds life-size statue of Saint John the Baptist made of terra - cotta glazed entirely milky white. It was recently rediscovered in the museum's storage and attributed to Giovanni Francesco Rustici , a collaborator of Leonardo da Vinci.

With his intense gaze, curly, shoulder-length hair, animal fur garment, and slender, bare-limbed body assuming a languid pose, this Saint John looks like a 1980s rock star. He's a Christian icon, but the loving attention to his physique harks back to the Greeks and Romans while announcing the advent of a new, human-centered universe.

The realism in Renaissance sculpture is wed to idealism: The body is seen with anatomical accuracy, but the people represented are usually the most excellent of specimens. See, for example, "'Rape of a Sabine Woman," a pedestal-size bronze believed to be from the workshop of Ferdinando Tacca : A powerfully muscled man lifts a beautiful, wildly gesturing woman in what looks more like a ballet move than a violent abduction.

It was more than just a cult of the body. The beautiful body stands for -- is one with -- the beautiful mind. This was a moment when the potential of human ingenuity to create a new world in its own terms -- as opposed to the terms of a distant, abstract God -- suddenly seemed limitless.

"Architecture," a small allegorical bronze by Giambologna from about 1600 that is one of the outstanding works in the MFA's collection, illustrates the point. It personifies the art of architecture as a voluptuous nude woman seated on a pedestal and holding drafting tools in her hands. For Renaissance artists it seems every endeavor was invested with erotic urgency. Even Giambologna's small, all-silver crucified Christ is an object of exquisite sensuousness.

Despite its extensive flirtation with ancient forms of paganism, the Renaissance did not do away with Christianity; rather, it humanized it. In the exhibition there are a number of Madonna and Child icons made of boldly colored glazed terra - cotta by one or another member of the della Robbia family (Luca , Andrea , and Giovanni are all represented.) Though almost unbearably pretty and sweet, the virgin mothers in these works look like real young women, and their babies are fat and lively. This is warm and humane, down-to-earth Christianity.

In this regard, see also a bust of Christ from about 1500, thought to be by Cristoforo Solari. He's no tortured martyr but a handsome, burly, bearded fellow with ringlets falling to his shoulders. Tilting his head slightly, he projects a genial, forgiving attitude. He looks like a guy you'd like to sit and have a beer with.

For me, the best of the della Robbia terra - cottas is a small "Head of Flora," dated about 1500 and attributed to Giovanni. Broken off at the neck from a larger statue, the head of a young woman glazed white with a colorful wreath of flowers in her hair has a mysterious, slightly perplexed look; she might be about to smile, like Leonardo's Mona Lisa.

One room in the exhibition has been set up to evoke the Renaissance "studiolo," a back room where the man of the house would retreat for rest, study, and contemplation in the company of small works of art and other collectibles. Displayed on shelves and in cases of natural wood are dozens of bronzes of all sorts: medals, mythological figures, portrait busts and fanciful inkwells in the form of a frog and a bizarre sea monster.

In a glass case in the center of the room, there's a small sculpture by Francesco Fanelli of a rearing horse. A label notes that this was "one of the quintessential subjects of Renaissance art" and that "the actions of a powerful and not always easily controllable animal represented a kind of view into the forces of nature." It occurs to me that the wild horse could also represent the volcanically creative human potential -- part spiritual, part instinctual -- that was pent up during the Middle Ages and released by the Renaissance, an energy that would require all kinds of artistic ingenuity to contain and give form to.

Going by wall labels, there are a half-dozen works in the exhibition that once were but are no longer thought to be genuine Renaissance products. Having these doubtful items included in the show has the unexpected, beneficial effect of sharpening one's perceptions.

Would my suspicions have been aroused by the extraordinarily elegant "Bust of a Youth" carved from marble in the manner of Mino da Fiesole -- whose genuine, 15th-century marble reliefs portraying Roman types are displayed along with it? Probably not -- for one thing, I thought it was a portrait of a woman. But on learning that it's believed to be either a fine example of 19th-century Renaissance Revival style or a brilliant fake, I studied it carefully. The downcast eyes and the cap-like hair style give it away, says the label. I was convinced, but I don't know what I'd think if there were no label. Either way, it's a beautiful object.

I found myself looking at everything else more searchingly and skeptically, asking, what are the visible signs of a true work of the Renaissance -- or of any period, for that matter? The general features are easy to discern; the truth is in subtleties that elude inexperienced eyes. The idea of looking in this way, of learning to see the world as well as art with such finely discriminating, empirical vision -- that in itself is a legacy of the Renaissance. It remains infectiously alive in this captivating exhibition.

Ken Johnson can be reached at kejohnson@globe.com.