When the artist joined the marchesa's circle

THE year was 1536. Michelangelo had just begun the huge fresco ''The Last Judgment.'' Always overworked and solitary, the artist had never found opportunity to manifest great sentimental impulses except in works of art. Now he was presented to the Marchesa Vittoria Colonna.

Vittoria, one of the noble Colonnas of Rome, was the devout widow of Don Ferrante d'Avalos, Marchese of Pescara, fatally wounded while serving as general in northern Italy for the Spanish king of Naples. She ranked among the best poets of Italy and was widely celebrated for charm, culture, social position, and education. The Marchesa could have enjoyed a life of worldly acclaim; instead, she chose the peace and seclusion obtainable in monastic establishments.

What did Vittoria look like? In the fascinating portrait by Girolamo Muziano in the Colonna Gallery in Rome, we see a lovely face crowned by bright golden hair of the tint Titian so loved to paint.

And Michelangelo? Fiercely dedicated to art, self-reliant, rugged, stern, he was no courtier, although no stranger to court society. As a young prodigy living with the Medici family in Florence, he had been treated by Lorenzo the Magnificent like another son. Among Michelangelo's acquaintances through the years were popes, princes, and philosophers.

There grew up between Michelangelo and Vittoria a rapport described by her as ''a steadfast friendship tied in a Christian knot of sure affection.''

Various people of exceptional intellectual and moral quality continued to seek her counsel, as they had done for years. Included were men of letters and high ecclesiastics. She was proud to welcome Michelangelo to that circle. Vittoria, an accomplished conversationalist, could get the laconic artist to talk at length.

The artist delighted in seeing the illustrious lady as frequently as possible , listening to her voice, never having the courage to reveal the depth of his feelings. The pious Vittoria, aware of all, accepted this true, sincere emotion and cherished it, glad to bring happiness to the great genius in whose art there is hardly ever a trace of a smile.