Richard D. Heffner, who was the host of PBS' The Open Mind passed away at the age of 88 on Tuesday in New York City.

The former head of the Motion Picture Association of America died of a cerebral hemorrhage, according to his wife, Elaine, Deadline reports. While he was head of the MPAA, the NC-17 and PG-13 ratings were established.

Heffner always regretted not properly introducing the NC-17 rating, saying in an interview with Variety in 1994, "It was clear we needed a public service campaign. A mistake was made in not educating the public" about the NC-17 not just being a rebranded X rating.

The Open Mind was broadcast every Saturday beginning in 1956 until his passing. Segments of the show that have already been taped will still air, according to The New York Times.

The show often discussed controversial subjects, even from its start, some topics covered on the show include segregation, anti-Semitism, homosexuality, alcoholism and McCarthyism. The Open Mind had such guests as Dr. Martin Luther King Jr., Malcolm X, Gloria Steinem, Thurgood Marshall and many others.

He also interviewed Eleanor Roosevelt on the eighth anniversary of President Franklin D. Roosevelt's death.

In addition to his work on TV and the ratings board, he was a historian and published A Documentary History of the United States, which is currently in its eighth edition.