Al Held, 76, an American artist who painted large-scale abstract works that contained a dizzying array of perspectives and optical effects, was found dead July 27, floating in a swimming pool at his villa near Camerata, Italy. The cause of death was not reported, but Italian police said he died of natural causes.

A streetwise New Yorker and Navy veteran, Mr. Held embodied a number of contradictions in his art and life. He was a high school dropout who became a professor at Yale University. He was well schooled in the classical tradition of Western art yet worked in an abstract style that suggested the time-warp universe of space flight. Without using computers, he brought a mathematical precision to the exuberant, loosely disciplined abstract expressionist style.

Mr. Held would spend as much as three years on one of his large-scale works, which sometimes measured more than 30 feet in length. Without belonging to any particular school of painting, he touched on several styles, from abstract expressionism to op art, illusionism, minimalism and hard-edge.

Anything but self-revelatory, Mr. Held's art was built on visual liveliness and density for its own sake. He used straight edges, masking tape and multiple coats of evenly applied paint to create works with intersecting lines, overlapping circles, triangles and other geometric figures. With subtle splashes of color and illusions of three-dimensional depth, the paintings could, in the words of one critic, be "disorienting to the point of vertigo."

Writing in ArtNews magazine in 1988, critic Nancy Grimes called Mr. Held's work "a refreshing alternative to Abstract Expressionism's tormented vision of an imperiled self."

He struggled in his early years, holding down blue-collar jobs while finding his artistic voice. But when he developed his geometric form of abstraction -- blending the randomly dripped paintings of Jackson Pollock with the meticulously ordered canvases of Piet Mondrian -- Mr. Held found a formula that served him well.

"The best abstract painting transforms its formal qualities into metaphors for truths unavailable to direct perception," he said.

He recently had completed an underground mural in the New York subway system at East 53rd Street and Lexington Avenue and was working on other murals in Florida and elsewhere. Busy until the end, Mr. Held could command more than $1 million for his more monumental works. He felt proprietary about his paintings long after they were completed and would oversee a team of artists whenever his murals needed touching up.

One of his larger pieces, measuring 16 feet high and more than 50 feet wide, is "Mantegna's Edge" (1983), originally done for an office building in Dallas and housed in the entry of the Boca Raton Museum of Art in Florida.

"Three of four weeks ago, I got a call from the front desk, saying there was a man in the museum who was touching the painting," said George S. Bolge, the museum's executive director. "When the guard explained that he couldn't touch it, he said, 'It belongs to me.'

"I came down, and it was Al. We went across the street and had a couple of drinks."

Mr. Held was born Oct. 12, 1928, in Brooklyn, N.Y., and moved to the Bronx in his early teens. Kicked out of high school at 16 for truancy, he later received a diploma from night school. After two years in the Navy, he returned to New York and got caught up in a circle of leftist artists and activists.

In 1948, he entered the Art Students League without ever having set foot in a museum. His works hang in the Metropolitan Museum of Art, the Museum of Modern Art and the Whitney Museum of American Art in New York and the Hirshhorn Museum and Sculpture Garden in Washington.

He studied in Paris and San Francisco in the early 1950s, then worked several years as a carpenter, truck driver, construction worker and mover. In 1959, when he switched from oil paint to acrylic, he began to experiment more freely with geometric patterns in his work.

From 1967 to 1978, he worked exclusively in black and white before reintroducing accents of color. He worked on his large canvases at his home in Briceville, N.Y., and spent summers in Italy, where he painted watercolors. Throughout his career, he maintained an allegiance to abstract art, which he considered the highest state of painting.

"He was incredibly intelligent and thoughtful about the meaning of abstraction," said Richard Lytle, an artist who taught at Yale with Mr. Held. "He felt when any artists gave up on abstraction, they were giving up the faith."

Mr. Held's marriages to Giselle Wexler, Yvonne Raier and Sylvia Stone ended in divorce.

Survivors include a daughter from the first marriage.

Al Held, who died at 76, maintained a commitment to abstraction throughout his career.