Leonard Cohen The Poet, Writer, And Father Leonard Cohen died in 2016, leaving behind many unpublished poems and lyrics. His son Adam Cohen discusses 'The Flame,' a collection of some of Leonard's final works. Adam remembers when his father was composing his best known song, Hallelujah. "It took him 12 years. It started when I was very, very young. I'd hear verses, I think there are 84 verses to that song," Adam says.