Music maestro A.R. Rahman got a little nostalgic remembering his old days, during the launch of his biography "A.R. Rahman: The Spirit of Music" in Mumbai Wednesday night.

The book has been penned by renowned writer Nasreen Munni Kabir.

The launch was also attended by Rahman's family, including his wife, sister and mother and filmmakers like Mani Ratnam, Ram Gopal Varma, Subhash Ghai, Ashutosh Gowarikar and Imtiaz Ali.

"I want to thank Munni for having the patience to sit with me and do this and to have an intension to do this, " Rahman said.

"While working on this book with Munni, I relived many old memories. But the one moment that I relived and can never forget was when I had no money to buy any equipment. I needed four lakh rupees and I didn't have that money. So my mother immediately sold off my sister's jewellery and gave me the money, " he said.

The book will provide a fascinating window into the world of the "Mozart of Madras", who became the first Indian composer to win two Academy Awards for the 2008 blockbuster "Slumdog Millionaire".

Talking about her experience of writing the book, Kabir said: "The idea of writing this film was actually trying and finding a way of creating a conversational biography that would record a person's thinking, a sweep of one's life upto now and some understanding of his craft and his personality."

She thanked Rahman for giving her the opportunity to write the book.

The book took approximately eight years to finish, and Kabir said she witnessed no major changes in Rahman in all these years, even though his popularity rose manifold during the course of this period.

"The interaction with Rahman took place in many countries, spread over many years. He has changed a little bit. The core person is the same but the life is different. There are lot more pressures, tremendous success but he wears his success lightly, which means that he is still very humble about it and the people he respected and regarded then are the same people, he respects and regards even now, " the author said.