The man formerly known as Cardinal Joseph Ratzinger - now Pope Benedict - has finished the first volume of a book on the life of Jesus Christ and has decided to publish what he has written so far because he doesn't know "how much time and strength" he has left, Reuters reports. The Vatican said on Tuesday the first volume, "Jesus of Nazareth," a personal, historical-theological analysis of Jesus as the central figure of the Christian faith, would be published in the spring by the Vatican's own publishing imprint, to be distributed by Rizzoli.

n an advance copy of the preface released by the Vatican, the Pope says the work is the fruit of "a long personal journey" that began when he was a young man in the 1930s in his native Germany. He says he started writing the book during his summer holidays in 2003 when he was Cardinal Joseph Ratzinger and has been dedicating "every spare minute" to the project since his election. "Because I don't know how much time and how much strength will still be granted to me, I have decided to publish the first 10 chapters as the first volume," he writes in the preface.