Gerontocracy has a dismal reputation. Even though we in the West live in aging societies, we are suspicious of the old, especially when they wield power. We associate youth with democracy, age with the tyranny of an autocrat or oligarchy. We think of the last years of the Soviet Union or communist China today. The image of the dictator is usually an elderly man in uniform: Tito or Mao, Franco or Castro, Hitler or Stalin. We forget that all these despots were comparatively young when they came to power. We tend to forget the rarer, often more benign examples of those who achieved power only in old age: Churchill and Adenauer, Reagan and Mandela.

Though women live longer than men nowadays, gerontocrats are almost always men. For every Elizabeth or Victoria, there are many Louis XIVs. Even biblical figures such as Abraham and Moses suffered from the feminist prejudice against patriarchy. This ageist bias helps to explain why the most prominent institution to embrace gerontocracy – the Roman Catholic Church, and the papacy in particular – gets such a bad press.The abiding impression of celibate old priests telling young people how to live their lives is not appealing to modern sensibilities.

The late Pope John Paul II proved a partial exception to this rule. Not that he escaped the hostility to which all popes are subject: Indeed, ageism was only one of many prejudices with which he had to contend. Other reasons for disapproval included being a superstitious Polish peasant, being a cloistered intellectual, being too conservative; being not conservative enough; being too much of a globetrotting populist; centralizing too much authority in Rome; being too autocratic; and being a puppet of the Curia. It soon became clear John Paul II would take no notice of these accusations. Indeed, he was as stubborn in resisting pressure to adapt the teaching of the Church to suit the world around him as he had always been in resisting Polish communism.

As the Pope and his critics aged, something extraordinary happened: He became the Vicar of Christ, not only for Catholics, but for the world at large. That ancient pontifical title, which casts the successors of St. Peter as the apostolic representative of God on earth, describes precisely the unique devotion this Pope inspired. By the manner of his death, no less than his life, he was transfigured into saint and martyr. Having survived assassination, he endured gradual immobilization until finally he was deprived even of the power of speech. The indomitable, dying Pope accomplished what Thomas a Kempis meant by “the imitation of Christ.” Yet from his deathbed, he radiated joyful anticipation of the life to come. John Paul the Great (as he was becoming known even before he died) made the medieval concept of the imitation of Christ seem the most natural thing in the world.

Any successor of this suffering ascetic would find him a hard act to follow. And when Cardinal Ratzinger emerged onto the balcony of the Vatican after the conclave, the dismay of the secular commentators was palpable. This, we were told, was the Grand Inquisitor, the former member of Hitler Youth and Wehrmacht, the least Christ-like shepherd the cardinals could have chosen. But Benedict XVI immediately disarmed his critics; not by abandoning the combative style that had led him on the eve of the conclave to denounce “the dictatorship of relativism” but by reaching out in his first homily as pope to the rest of Christendom and beyond, to “you, my brothers and sisters of the Jewish people, to whom we are joined by a great shared spiritual heritage, one rooted in God’s irrevocable promises.” It is clear that Benedict, one of the prime advocates of John Paul’s historic reconciliation with Judaism and the Jewish people, now intends to lift that dialogue onto an even higher plane.

It would be premature to compare the records of these two popes, one of whom occupied the throne of St Peter for 26 years, the other for not yet 26 weeks. But one can compare their biographies, which tell us as much about their authors as the subjects.

Gary O’Connor’s “Universal Father: A Life of John Paul II” is an honest attempt to do justice to a figure not larger but greater than life. The author is an experienced biographer who hitherto specialized in such theatrical subjects as Ralph Richardson (the book that made his name), Shakespeare, and Alec Guinness. One reason, indeed, for his interest in John Paul II is the little-noticed dramatic career of this playwright pope. Mr. O’Connor is excellent not only on the young Karol Wojtyla’s plays, but on the poetry, philosophy, and spiritual meditations that expressed his innermost beliefs. “Universal Father” does not replace the monumental life by George Weigel, “Witness to Hope.” But it is a warm, humane, and lively portrait, fresh and original in its depiction of the pope as a man of letters. Its brevity is matched by its wit.

The same cannot be said for John Cornwell’s “The Pontiff in Winter: Triumph and Conflict in the Reign of John Paul II.” This mean-spirited hatchet-job, which appeared shortly before its subject’s death, is the latest diatribe by the author of “Hitler’s Pope,” a sensationalist and one-sided character assassination of Pius XII. Remarkably, there is a partial retraction of “Hitler’s Pope” in this new book: “I would now argue … that Pius XII had so little scope of action that it is impossible to judge the motives for his silence during the war, while Rome was under the heel of Mussolini and later occupied by the Germans.” So why has Mr. Cornwell not withdrawn his book, or at least altered its hateful title?

Mr. Cornwell’s charge against Pius was that he watched callously as the Nazis carried out the Holocaust. His charge against John Paul is that “he has run the papacy as if he were a Superman.” No pope, whether active or passive, is good enough for this biographer. Mr. Cornwell finds space for the novelist Graham Greene’s glib comparison of Wojtyla and Ronald Reagan (“They were both world leaders who were in fact just actors”) but devotes next to no space to John Paul’s doctrinal legacy – his encyclicals, or the new catechism, or the new spiritual movements. Even undisputed achievements, such as the pope’s part in the fall of communism or his rapprochement with the Jews, are interpreted maliciously or conspiratorially. Perhaps he should have called this book “Reagan’s Pope.”

Benedict XVI’s biographer, John L. Allen Jr., does at least pay his subject the compliment of taking his vast corpus of writings seriously. But “Pope Benedict XVI: A Biography of Joseph Ratzinger” is not quite what it purports to be. Though it has been retitled since the new pope took office, the book first appeared five years ago and has not been updated since. This seems to me to be an astonishing dereliction of the author’s duty to his readers. The book still includes a long section on “Ratzinger and the Next Conclave,” which concludes that the cardinal is unlikely to be pope and that in the unlikely event of his election he would take the name Pius XIII. It is bizarre for a writer to draw attention to his own false predictions by republishing them unaltered. At the very least, Mr. Allen’s considered judgment that Pope Benedict has “fallen short of greatness” ought surely to have been reconsidered with his pontificate still in its infancy.

Mr. Allen, who is the Vatican correspondent for the National Catholic Reporter, is fair enough in his treatment of Benedict’s early life and intellectual formation, but out of his depth in the great theological disputations that have dominated his career as prefect of the congregation for the Doctrine of the Faith, the former Holy Office. His focus as reporter for an American audience causes him to give too much weight to relatively minor incidents merely because they concern the United States. And his own prejudices – in favor of national bishops’ conferences, women priests, or homosexuals against Rome – are too overt. As a liberal “Vatican II Catholic,” Mr. Allen has made a genuine effort to engage with Benedict’s austere conception of the church’s place in the world of thought. But the effect of his polemics is to expose the superficiality of his own brand of Catholicism rather than to refute that of the pope.

To grasp how Benedict sees his mission, the reader would do better to read the new anthology of his writings by Robert Moynihan: “Let God’s Light Shine Forth: The Spiritual Vision of Pope Benedict XVI.” Preceded by a biographical essay, this thematic collection includes the new pope’s first pronouncements and will doubtless be added to as his pontificate progresses. The overall impression is not of fear and loathing, as the pope’s critics allege, but of sublime cheerfulness and serenity. Benedict’s reply to his critics is characteristically robust: “I’m only afraid at the dentist.” He does not have the physical presence of his predecessor – the professor compared to the prizefighter – but Benedict does not lack courage. Over the coming months and – God willing – years, he will certainly need it.

Mr. Johnson writes a column for the foreign pages of The New York Sun.