Art Garfunkel on life's "little insights" and his "intense" relationship with Paul Simon

Art Garfunkel's voice helped shape some of the most famous songs in American music. As half of the duo Simon & Garfunkel, his pipes dominated the pop charts with hits like "Bridge Over Troubled Water," "Cecilia" and "Homeward Bound" and multiple No. 1 records.

Later he moved onto a successful solo career. The acclaimed singer told "CBS This Morning" on Tuesday that he never planned to write a book, but after years of jotting down insights in a small notebook he keeps tucked in his back pocket, he decided to put together a memoir.

"What Is It All but Luminous: Notes from an Underground Man," chronicles his life, career-defining moments and tumultuous relationship with Paul Simon.

"I've walked the United States and I've walked across Europe. As I walk, little insights occur to me, some of them are big and I get a notion of a first line and I go, that line has rhythm and it means something to me. It touches the theme I've thought about all my life," Garfunkel said.  

Garfunkel's voice helped Simon & Garfunkel earn induction into the Rock and Roll Hall of Fame and a Grammy Lifetime Achievement Award. Early on, Garfunkel knew he had a gift and often sang at his temple as a young boy – a place that influenced his style.

"It gave me a spirituality connected to singing right from the earliest age. So you share it with others," Garfunkel said. "The temple had a big high ceiling with lovely wood walls so the reverb was wonderful and that became a big thing for me. The echo which puts tails on your notes and extends them, I was entranced with that sound."

After Simon & Garfunkel split in 1970, it was his voice that gave him confidence.

"I didn't know if the world would accept me, but I knew I could sing without Paul," he said.

He described the duo's relationship as "intense" and "like a marriage."

"It has summers and winters. It waxes and wanes, it is best not talked about. You leave it alone. Sometimes you get a call from Paul or I from him, and out of nowhere something funny goes on and you laugh and you go, I miss him, and then you hang out, you have a dinner," Garfunkel said. "It's standard to be asked, 'Do you think you'll work together?' And I've always said, 'Who knows, life is a surprise.' We don't know what comes next. Nowadays, I say, 'No, we won't.'"

Asked what the "luminous" referenced in his memoir's title means, he said, "It's as if you're walking and you are so entranced by the beauty of everything you tear up and in the blurry vision of tearing up, what is it all but luminous? It's a poet's notion."

In the book, a travelogue of sorts, he described the songs that changed his life, including songs from The Beatles and one of his own.

"'Scarborough Fair' felt to me like the best, most flowing, most organic thing we ever recorded."