Joshua GreeneTo biographer Joshua Greene, George Harrison's spiritual life was just as important as his well documented musical role as one of The Beatles.

Greene's new book, Here Comes the Sun: The Spiritual and Musical Journey of George Harrison, was sparked by his memories of a meeting with Harrison in December 1969 when the writer was a 19-year-old organ player and Harrison was one of the world's most famous musicians.

Harrison, who died from cancer in 2001 aged 58, was the man who, along with his first wife, Patti Boyd, brought Indian mysticism and the Maharishi to the Fab Four. He introduced the sitar to pop music in Norwegian Wood and went on to become a devotee of the International Society for Krishna Consciousness.

"The book covers his journey to enlightenment," said Greene, who himself spent 13 years in a Hindu ashram before becoming an instructor in the religions department of Hofstra University. "George had everything, fame, money, but he was motivated by knowledge. He didn't succumb to his success like so many other superstars.

"When I met him, I was stunned at how warm a human being he was. He did not have an iota of pretense about him. He clearly didn't enjoy being treated differently to anyone else. His quest for spirituality caused a big stir at the time and was a surprise to many people. Many people questioned why he was doing it and asked ‘where's our George?'"

Greene conducted around 25 to 30 interviews for the book, including musicians who worked with Harrison, Krishna devotees, his sister Louise and cultural icons like Donovan and Mia Farrow.

"I learned George was on a serious spiritual quest," continued Greene. "When someone does this, they cannot enjoy material possessions anymore. He was trying to confront his biggest fear which I think was anger. It's easy to change things like diet, sexual habits and drugs, but it is much harder to change the subtle things about life. He was angry that he had been robbed of his privacy and people were prepared to exploit him at every opportunity because of who he was."

Greene explains Harrison's quest for spirituality also turned him on to reading. "George was a terrible reader as a young man," he said. "After going to India, he became a greater reader and always carried books around with him. He gave away thousands of copies of Autobiography of a Yogi and The Science of Self-Realization."