Paul VI would never have had the courage which enabled his predecessor, Pope John XXIII, to call the Second Vatican Council and set in train its reforms. 'This holy old boy doesn't realise what a hornet's nest he is stirring up,' he is reported to have commented when he heard of the proposal. Yet he pushed forward the changes begun by the charismatic John.
His most important decision may not have been on birth control but his backing for the vernacular mass, Hebblethwaite suggests. In international affairs he argued, controversially, that the wealth of rich countries should be used to benefit poor nations. He was the first pope to visit Latin America, and he attended a meeting of priests at Medellin which encouraged the emergence of liberation theology. For the first time in history, a local Catholic church was allowed to control its own destiny.
During his time in the Vatican, relations with other churches improved steadily. While the visit of the Archbishop of Canterbury, Dr Geoffrey Fisher, to his predecessor was a hole-in-the- corner affair, that of Dr Michael Ramsey was greeted by Paul with public enthusiasm. Even women did as well as could be expected out of his pontificate - the pronouncement, in 1976, that they should not be ordained priests was not presented as a definitive statement for all time.
If his story lacks the drama of a Hamlet or a Don Quixote, the picture of an intense, worried, diplomatic and very talented holy man is well and sympathetically painted. Yet there are tantalising omissions in the book's 710 pages.
What really motivated Paul VI in turning down the advice of the Birth Control Commission? The account is disjointed and unsatisfactory. The 'thin-end-of the wedge' argument clearly played a part: how could you limit birth control to good Catholic families who had already produced the requisite number of children, as his opponents argued? The pope also complained of being overwhelmed by documents, a remark which cut little ice, Hebblethwaite says, with families who were overwhelmed by children.
Perhaps the clue lies in the weight of tradition which shackles any pope, and in Vatican intrigues. The book has telling passages about both. Twenty-three cardinals voted against Paul VI's election and one was so appalled by the 'squalid manoeuvring' that he broke with tradition and protested publicly during the conclave.
Paul's speeches about his personal beliefs contrast movingly with this squalor. In 1957 he urged his listeners to love Muslims, pagans, persecutors and atheists, radical stuff for conservatives who had just seen Khrushchev suppress the Hungarian revolution. Such themes, however, are hard to unravel from this chronological account: it is as though Hebblethwaite, like his subject, has been overwhelmed by too much evidence.