The sudden hospitalization of Pope John Paul was another reminder, if any were needed, that one of the longest and most event-studded pontificates in history may be coming to a close.
The 84-year-old Pope was rushed to Rome's Gemelli hospital with breathing difficulties late on Tuesday night after a bout of influenza suddenly deteriorated.
While a Vatican statement on Wednesday morning said his condition had stabilized after assistance with his breathing, the thought going through many minds was: "Who will be next?"
John Paul, now in the 27th year of his reign, is already the third-longest serving Pope in history, having been elected in 1978 as the first non-Italian Pontiff in 455 years.
The little-known candidate chosen nearly three decades ago electrified the world. He set more records than all of his predecessors, not just preaching but writing, traveling and even skiing.
Yet he perhaps divided Roman Catholics more than any other Pope in memory.
Liberal Catholics have balked at bans on female priests, contraception and gay marriages. They have made it clear they want a more democratic Church in the future.
Conservatives hailed him as a divine messenger who took a Church buffeted by the winds of liberalism in the 1960s and 1970s and put it back on the theologically straight and narrow.
A man of towering intellect and intensity of prayer bordering on mysticism, Karol Wojtyla was one of the few Popes in centuries to have come up from poverty rather than through privilege.
Historians say this and a succession of personal tragedies that caused him to turn inward early in life gave him the reservoir of resolve he drew on to stand up to communists in his Polish homeland and later to dissenters in the Church.
Critics, particularly those in developed countries, faulted him for applying to issues of faith and morals the same uncompromising style that served him so well in staring down the communists and keeping his Church alive in Poland.
TOWERING FIGURE
Can anyone succeed such a towering figure without appearing a mere shadow of Wojtyla?
That is the dilemma that cardinals, the red-hatted "princes" of the Catholic Church will face when they meet in a secret conclave after the death of the current Pope -- whenever it may be -- to choose a successor from among themselves.
The Pope has appointed nearly all of some 120 cardinals currently aged under 80 who can enter the conclave, stacking the odds that the new leader will think like him and not tamper with rulings like the bans on contraception and women priests.
The main question is whether the next Pope should be another non-Italian, whether the Italians should get the papacy back or whether the next Pope should be a non-European.
A number of Churchmen believe that the developing world should provide the next Catholic leader because that is where the religion is most vibrant and growing.
Weighing on cardinals' minds will be the fact that nearly 65 percent of the world's Catholics now live in Africa, Asia and especially Latin America.
Another concern for the cardinals is the need they see to preach Christianity more vigorously in Western societies that are now marked far more by materialism and individualism than by the self-sacrifice the Church preaches.
John Paul has pioneered inter-faith relations, especially with the Jews, but will leave behind unfinished business.
In an increasingly globalized world, Catholicism will more than ever need to cooperate with other religions it previously fought against, condemned or ignored, experts have said.
Every time the Pope's health has wobbled in recent years, pundits have tried to predict who would be the next Pope. A succession of front-runners have died as the current Pope soldiered on despite his frailty.
Now, a question mark is again hanging over the Gemelli hospital, over the Vatican, and over the Catholic world.