Marcus Raskin, an author and advocate who helped shape left-leaning thought for decades as a founder of one of Washington’s most prominent liberal think tanks, the Institute for Policy Studies – and who, as a college student, gave piano lessons to composer Philip Glass – died Dec. 24 at his home in Washington, D.C. He was 83.

The cause was a heart-related ailment, said his son Jamie Raskin, a Democratic member of the U.S. House from Maryland.

Raskin, a child prodigy on piano and a University of Chicago Law School graduate, joined President John F. Kennedy’s administration while still in his 20s. He went on to become the author or co-author of more than 20 books on foreign policy, civil rights, political philosophy and the “national security state,” a term he originated in the early 1970s to describe a military, intelligence and security network that exists with little legal supervision.

From civil rights marches to antiwar protests to the Pentagon Papers, Raskin was a persistent and ubiquitous intellectual provocateur of the left. He and his fellow founder of the Institute for Policy Studies, Richard Barnet, were on President Richard M. Nixon’s enemies list in the early 1970s.

“What we’re playing for,” Raskin told The Washington Post in 1986, “is the spirit of the time.”

Raskin was the co-editor of “The Viet-Nam Reader” (1965), an influential historical anthology about Vietnam that helped inspire “teach-ins” about the war at colleges throughout the country. In 1968, he went on trial as part of the Boston Five for conspiracy to help young men avoid the military draft during the Vietnam War.

His four co-defendants – pediatrician Benjamin Spock, Yale University chaplain William Sloane Coffin, writer Mitchell Goodman and graduate student Michael Ferber – were sentenced two years in prison by a judge who likened their actions to treason. Raskin was the only one found not guilty.

“I suppose I could demand a retrial,” he said afterward. (The other defendants were acquitted on appeal.)

Despite its intellectual heft, the Institute for Policy Studies was often run on a shoestring. As a matter of principle, it accepted no money from corporations or the government. It survived on grants from private foundations and individuals.

For years, the institute was housed in a shabby building near Dupont Circle, in which paint was peeling and the elevator didn’t work. Senior fellows sometimes took turns running the switchboard.

Nonetheless, it was a heady environment abuzz with many of the leading liberal thinkers, writers and political figures of the day. Raskin often contributed to the Nation and the New York Times, and Barnet, who died in 2004, frequently wrote for the New Yorker and the New York Review of Books. Both churned out books, often together.

Others affiliated with the institute included 1972 Democratic presidential candidate George McGovern, writer and civil rights activist Roger Wilkins, documentary filmmaker Saul Landau, writer Barbara Ehrenreich and poet Ethelbert Miller.

Raskin and the institute were sometimes under surveillance by the FBI and became favorite targets of right-wing publications and ideologues, who charged that it was part of a Soviet-inspired Marxist cabal. Yet the institute went on unabated, even after the Soviet Union disappeared.

In some ways, the IPS was so successful that it became the model for a later generation of conservative think tanks, most notably the Heritage Foundation, which was founded in 1973.

“The thought occurred to me,” Paul Weyrich, the Heritage Foundation’s first president, told The Post in 1986, “that if an operation as overtly left as IPS could get by with having an impact on the Hill, then a respectable conservative institution could have an even greater impact.”

In 1971, Raskin surreptitiously received “a mountain of paper, some 2,000 to 5,000 pages,” that turned out to be excerpts from the Pentagon Papers, a secret government publication detailing the history of U.S. involvement in Vietnam.

The papers came from Daniel Ellsberg, a onetime government consultant. Raskin reportedly put Ellsberg in touch with New York Times journalist Neil Sheehan, who wrote a Pulitzer Prize-winning series of articles based on the papers.

In the 1970s, one of the fellows at the Institute for Policy Studies was Orlando Letelier, a onetime Chilean official who was arrested after a right-wing regime led by Augusto Pinochet seized in the country in 1973. Letelier was assassinated in a car bombing on Embassy Row in 1976 while driving to the institute’s office. Also killed was Ronni Karpen Moffitt, who was an assistant to Letelier and Raskin.

Several people were prosecuted and sent to prison in the United States and Chile, but Pinochet was not among them.

Marcus Goodman Raskin was born April 30, 1934, in Milwaukee. His father was a plumber, his mother a seamstress.

Raskin began playing piano at 4 and by the time he was 12, he was featured on a weekly radio program. He left high school to study at the Juilliard School in New York under acclaimed teacher Rosina Lhevinne.

At 16, Raskin decided to give up music as a career.

“One, there’s an enormous amount of nervous tension involved – even when you’re playing just for yourself,” he told the Dallas Morning News in 1999. “Anyone with the slightest anxiety complex ends up in trouble. The other reason is laziness.”

He transferred to the University of Chicago, where Glass, a student in the same dormitory, sought him out.

“I asked Marcus for help with the piano, and he became my piano teacher,” Glass wrote in his 2015 memoir “Words Without Music.” “With him I started on a real piano technique, and he was serious about my progress.”

Raskin graduated in 1954 and received a law degree, also from the University of Chicago, in 1957. He studied piano in Italy for a year before moving to Washington in 1958.

He worked on Capitol Hill before joining the Kennedy administration as a deputy to national security adviser McGeorge Bundy. After the failed U.S.-sponsored invasion of Cuba at the Bay of Pigs in 1962, Raskin’s relations with Bundy and other officials grew more strained.

Barnet shared his disillusionment, and together they launched the Institute for Policy Studies in 1963.

Raskin’s books included “Being and Doing” (1971), “Notes on the Old System” (1974) about the Watergate scandal, “The Common Good” (1986), and “Liberalism: The Genius of American Ideals” (2003). In recent years, he also taught at George Washington University.

His first marriage, to Barbara Bellman Raskin, a novelist and journalist, ended in divorce. Survivors include his wife of 32 years, Lynn Randels Raskin of Washington; three children from his first marriage, Erika Raskin Littlewood of Charlottesville, Virginia; Jamie Raskin of Takoma Park, Maryland; and Noah Raskin of Vienna, Virginia; a daughter from his second marriage, Eden Raskin Jenkins; nine grandchildren; and a great-grandson.

In 1999, Raskin performed in a national competition for amateur pianists, playing works by Bach and Beethoven. Last year, he and Glass gave a benefit concert for Raskin’s son, then running for Congress.

Glass said he was nervous because he hadn’t played for his teacher in more than 50 years.