Sam Keen, the author and philosopher whose book Fire in the Belly: On Being a Man was a touchstone of the “men’s movement” of the early 1990s, died at 93, the New York Times reports.

Keen, a native of Scranton, Pennsylvania, was raised in Tennessee and Delaware and educated at Ursinus College, Harvard Divinity School, and Princeton University. He worked as a seminary teacher and freelance journalist, and during the 1960s and ’70s he wrote several books about spirituality, including Apology for Wonder, To a Dancing God, and Beginnings Without End.

He was the subject of a Bill Moyers documentary, Your Mythic Journey With Sam Keen, in 1991, shortly before Fire in the Belly came out. The book urged men to get in touch with their masculinity, and was published the year after a similarly themed book, poet Robert Bly’s Iron John: A Book About Men, was released.

The two books launched the men’s movement, which saw men attend retreats and workshops in the wilderness. The movement was briefly popular but also drew derision from some, including author Alfred Gingold, who parodied it in his 1992 book, Fire in the John: The Manly Man in the Age of Sissification, and Saturday Night Live, which skewered it in a skit called “I Am a Man.”

Keen’s other books include To Love and Be Loved, Hymns to an Unknown God, and Inward Bound.

In a 1999 interview with journalist Scott London, Keen said, “The spiritual mind is always metaphorical. Spiritual thinking is poetic thinking. It’s always trying to put a very diaphanous experience into words, realizing all the while that words are inadequate.…The God out of which we came and into which we go is an unknown God. It’s the luminosity of that darkness and that unknowing that is, I think, the most human—and the most sacred—place of all.”

Michael Schaub is a contributing writer.