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.
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.
The first book to be published by the 79-year-old Benedict since he became Pope in April 2005 will be distributed by Italian publisher Rizzoli, a unit of RCS Mediagroup, in cooperation with the Vatican's own publishing house.
In 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.
The Pope appears to be in generally good health, but since his election he has made several public references to being old and not knowing how much more time God will give him.
In the preface he says the first volume of the book will cover the life of Christ from his baptism in the River Jordan as a young man to the Transfiguration, when the gospel says three of his apostles saw his divine nature and had visions of Moses and Elijah.
The Pope says the book should not be considered part of official, binding Roman Catholic teaching but is "my interpretation of the figure of Jesus of the New Testament" and "solely a reflection of my personal research".
He adds: "Therefore, everyone is free to contradict me."
In his position as the Church's top theologian for more than two decades before becoming Pope, Benedict wrote dozens of books.
Last February, he issued his first encyclical, Deus Caritas Est (God is Love). Its themes ranged from erotic and spiritual love in a personal relationship to the role of the Catholic Church's vast network of charity organisations around the world.