The notion is an old one: Painters are a wild sort, steamy, unreliable, tumultuous in their passions. Their talent grants them license. They get to break the rules and get close to naked models and lead unfettered lives.

Glowing like a halo around Fra Angelico (c. 1390-1455) is the opposite idea.

More than 70 of his paintings, heavenly in color, are now at the Metropolitan Museum of Art. They do what they were meant to do, they fill your mind with shining. His Virgins sit on golden thrones, cloth of gold is everywhere, his angels dance in starry space in gold-embroidered gowns. Fra Angelico himself seemed to have about him a suggestion of sanctity. His artist friends remarked on it. The Vatican has noted it. By all accounts a humble, warm, obedient man, he got about as close as busy painters get to the company of the saints.

When Fra Angelico was born in the Mugello, north of Florence, the Gothic Middle Ages were already fading. When he died awash in honor 550 years ago, what we know as the High Renaissance was already in full bloom. His paintings build a bridge, delicate and gilded, between those realms.

His light feels somehow sweetened. The movements of his brush are blithe. His unexpected color chords (those celadons with purples, those fawn browns with mauves and pinks and greens) shape the most unlikely harmonies, buoyant and remote. He isn't very good at mathematical perspective. In the art of Fra Angelico, calculation matters less than inspiration. It isn't this world that he shows us, it's the next.

Fra Angelico is, by the way, not his real name. He was Guido as a kid, Guido di Pietro. When, between 1419 and 1422, he became a monk, an Observant Dominican, he switched to Giovanni. The "Fra" is short for "frater," brother. The "Angelico" is there because he painted like an angel. In 1984, the painter was renamed again, this time at his beatification by Pope John Paul II. Beato Angelico (the "Beato" means blessed) may someday be a saint.

So apparent was his sanctity that how much he'd be paid was entrusted to his conscience. In 1433, when he agreed to paint an altarpiece for the linenmakers' guild it was agreed that he would get 190 florins -- or however much less he considered proper.

When he took his vow of poverty he meant it. Like his brother Dominicans, Fra Angelico was a mendicant, which is a nice word for beggar. The Apostles had dedicated themselves to poverty and preaching, and living on charity, and so did he. He had no possessions. He had no property. He lived in a cell; he ate in the refectory; the money he earned painting he turned over to his order.

Giorgio Vasari, his 16th-century biographer, says this "simple and most holy" man would never lift a brush without first saying a prayer. And whenever he would seize his brush to paint a Crucifixion, "the tears would stream down his face."

When Pope Eugenius IV, suitably impressed, proposed to name the painter the archbishop of Florence, Fra Angelico, in humility, demurred. And "what seems to me extraordinary and almost unbelievable," adds Vasari, "is that the friars never saw him angry; if he needed to admonish his friends he did it smilingly, without fuss."

Impious modern viewers who prefer to take their art with a touch of vinegar or pepper may find this sweetness cloying, but the Victorians loved it. John Ruskin, for example, wrote that Fra Angelico ought to be approached as "not an artist properly so-called but as an inspired saint." When Ruskin's fervent painter friends, scorning the low crudities of industry and shopping, declared themselves "Pre-Raphaelites" it was relentlessly high-minded art like Fra Angelico's that they had in mind.

He didn't just paint his pictures. He hammered them. Fra Angelico would work in egg-based tempera on a wooden panel. His panels were first sanded smooth, then coated with a gypsum paste. Large areas of their surfaces -- instead of being painted -- were then coated with a thin layer of gold. Fra Angelico -- who'd begun by illuminating manuscripts -- would then proceed to work that gold the way a bookbinder gilds leather, with small metal punches, advancing tap by tap constructing not an image, but intricate decorative designs.

The gold-leafed surface gleams, of course, but so, too, do the incised angles of his punch-marks. Because the gold is faceted his paintings twinkle gently each time you move your head.

His pictures, perhaps, gleam too much. Fra Angelico himself may have welcomed poverty, but his art doesn't. His paintings invoke treasure. His sumptuous gold-ground pictures feel immensely rich. They may summon thoughts of Scripture, but because they smell of money, too, they also call to mind another world entirely, "which, for better or worse," wrote art historian Kenneth Clark, "is the ancestor of our own, the world of trade and of banking, of cities full of hard-headed men whose aim in life was to grow rich without ceasing to appear respectable."

In Fra Angelico's Florence one of these hardheaded men was Cosimo de' Medici. Men who were not monks were seldom allowed entrance to the San Marco monastery where they might see the painter's frescoes. Cosimo was different. He had his own apartments there. That's because he paid the bills.

Images constructed in accordance with the laws of mathematical perspective are a little bit like windows. You look not at but into them, deep into deep space. Fra Angelico's are different. That's because they're less like windows than they are like Gothic reliquaries -- those costly jeweled caskets specially constructed for the relics of the saints were often fitted with strong locks. Many of these pictures, too, came equipped with closing doors as if to hold in safety the treasures they contained.

Christians, then as now, sometimes found it tricky to faithfully subscribe to apostolic poverty while hungering simultaneously for power, cash and things. These gold-encrusted pictures resolve that old dilemma. Holiness or treasure? Why not have them both?

These aren't the finest Fra Angelicos. Those don't travel. The greatest of his frescoes are still attached to walls in Florence and the Vatican. Many others are too fragile to journey to New York.

Scholars Laurence Kanter and Pia Palladino of the Metropolitan Museum are primarily responsible for both the exhibition and its often arcane catalogue. Their exhibition is supported by a grant from the Homeland Foundation, and by an indemnity from the Federal Council on the Arts and the Humanities. It won't travel. The exhibition closes Jan. 29.

Riches of Heaven: "The Annunciatory Angel" from the New York exhibition of the Renaissance master's works.CREDIT: Museu Nacional d'Art de Catalunya, Barcelona CAPTION: Fra Angelico, "Virgin and Child, with Five Angels," tempera on panel.