PORTLAND — The lyrical quality of John Marin’s style — breaking away from exact shapes and introducing floating lines across his works in suggested dreamlike patterns — foreshadowed modern art in America.

Marin’s sweeping lines create a sense of place with touches of color, dashes of lines and half-suggested figures. The beauty of his work is that he does not define images rigidly. He is a master of suggestion.

The Portland Museum of Art is showing the best of Marin’s watercolors and oils done during the late part of his career. Born in 1870, the artist died in 1953.

Featured in the “John Marin Modernism at Midcentury” exhibit are 54 works, including many oil paintings — exciting to see because typically Marin’s watercolors, for which he is most famous, are on public display. The oils exhibited by the PMA are equal to but not better than his watercolors, in my opinion.

Beginning in the early 1900s, Marin spent summers with fellow avant-garde artists Marsden Hartley, William and Margeurite Zorach and Gaston Lachaise in midcoast Maine, finding inspiration in the beauty of the state’s islands, mountains, beaches and rocky coastline.

In 1933, he purchased a home in Cape Split, between Mount Desert and Eastport, where many of his greatest works were created. There, overlooking the ocean, he seemed to form a union with Maine’s natural beauty and was drawn to the power of the sea.

Marin sensed the radical potential of painting on Cape Split, transforming the ephemeral patterns of waves in their alternative states of turbulence and calm into innovative compositions, forecasting, as it turns out, some of the primary features and preoccupations of mid-century American art, according to the PMA.

But while the sea captured most of his interest in Maine, Marin also painted sites in New York and New Jersey, where he lived during winter months.

I would describe the “John Marin Modernism at Midcentury” exhibit as a blockbuster because of the outstanding quality of works and the opportunity to see pieces loaned by major museums across the country.

A lifesize photograph of Marin standing, taken by Irving Penn circa 1949, hangs in the center gallery as if he’s an actual presence in the exhibit.

Among the outstanding works in this exhibit are Marin’s “Wave on Rock,” 1937, an oil painting on loan from the Whitney Museum of American Art of New York; “Island (Ship’s Stern),” 1934, a watercolor on loan from Meredith Ward Fine Art of New York; and “Cape Split,” 1940, an oil painting on loan from Addison Gallery of American Art Phillips Academy in Andover, Mass.

Other works of significance include “The Written Sea,” 1952, an oil painting on loan from the National Gallery of Art of Washington, D.C.; “Movement: Sea, Ultramarine and Green; Sky, Cerulean and Grey,” 1947, an oil painting on loan from the Blanton Museum of Art, the University of Texas at Austin; and “Blue Sea, Red Sky, Ledges, Cape Split, Maine,” 1937, a watercolor and charcoal on paper on loan from the Colby College Museum of Art.

“It is quite possible Marin is the greatest living American painter,” wrote Clement Greenberg, an American essayist and renowned art critic of the Modernist era, in his book “Art and Culture: Critical Essays,” published by Beacon Press of Boston.

“John Marin Modernism at Midcentury” will be up until Oct. 10 and will then travel to the Amon Carter Museum in Fort Worth, Texas.

The museum at Seven Congress Square is open 10 a.m. to 5 p.m. Tuesday, Wednesday, Thursday, Saturday and Sunday; and 10 a.m. to 9 p.m. Friday. Admission is $10 for adults, $8 for seniors and students with ID, $4 for youths ages 6-17 and free for children under 6. Admission is free from 5 to 9 p.m. Friday.

Pat Davidson Reef, who holds a master’s degree in education, has written two children’s books, “Dahlov Ipcar, Artist,” and “Bernard Langlais, Sculptor.”

John Marin did this oil painting, titled “Cape Split,” in 1940.