Vatican City, Oct. 16-(RNS) Pope John Paul II, 81 years old and in failinghealth, Tuesday (Oct. 16) marked the 23rd anniversary of his election towhat has become one of the longest pontificates in the history of theRoman Catholic Church.

Congratulating the pope on behalf of 247 bishops from throughout theworld meeting at the Vatican, Cardinal Bernard Agre, archbishop ofAbidjan, Cote d'Ivoire, wished him "multos et faustissimos annos" (manyand most happy years) to come.

The Polish-born John Paul, chosen by the College of Cardinals onOct. 16, 1978, as the 263rd successor to St. Peter and the firstnon-Italian pope in 41/2 centuries, now ranks seventh in longevity ofservice. Agre praised the pope, who has traveled the equivalent of 28 timesaround the world or almost three times to the moon, as a "pilgrim ofhope and artificer of dialogue and peace."

No mention was made of his age and infirmities, but within thechurch concern is growing over what might happen if the once athleticJohn Paul were incapacitated by the neurological disease that alreadyhas made it difficult for him to move and to speak clearly.

Over the last two millenniums, papacies have ended only with deathor on extremely rare occasions with resignations. The last pope toabdicate was Celestine V, who left the throne of St. Peter in 1294, waspronounced a saint by the church but consigned to the inferno by DanteAlighieri in the "Divine Comedy."

John Paul, in his Apostolic Constitution on the Vacancy of theApostolic See and the Election of the Roman Pontiff issued in 1996,revised the procedure for the Conclave that will elect his successor. "There are, however, no canonical procedures for deposing animpaired, mentally deranged, senile, comatose or, even worse, amanifestly unworthy pope," Monsignor Charles Burns, a Scottish Vaticanscholar, pointed out in a recent study of the election process.

Despite signs of weakness and fatigue, especially during his tripsoutside Italy, John Paul has remained mentally alert and fully capableof dealing with the unexpected. He has ad-libbed and joked and even sangsongs from his Polish childhood during a meeting with young Ukrainiansin Lviv in June. Since January 1979, less than three months after his election, thepope has made 95 trips outside Italy, visiting 193 countries, and hisaides have said he has no intention of stopping his travels.

John Paul is expected to visit Belarus, Bulgaria and Moldavia inMay, return to Poland in June and preside over World Youth Daycelebrations in Toronto, Canada, in July. A trip to Moscow is a majorgoal blocked so far by strains between the Vatican and the RussianOrthodox Patriarchy.

Although he is said to use an electric cart to traverse the longmarble halls of the Apostolic Palace, the pope keeps to a demandingschedule of audiences six days a week. The Vatican said he has met withmore than 1,330 political leaders, and on Aug. 1 he held his 1,000thweekly general audience.

The pope also meets regularly with members of the Roman Curia, thechurch's central administrative bodies, and personally approves allimportant Vatican documents and key appointments. He has regularlyattended the twice-daily sessions of the monthlong Synod of Bishops nowmeeting at the Vatican to discuss the role of bishops in the 21stcentury.

In addition, John Paul has asserted his authority over the church'sMagisterium, or teaching, by publishing 13 encyclicals, 12 apostolicexhortations, 11 apostolic constitutions, 41 apostolic letters and 25"motu proprio," another form of message to the entire church.

And he has proclaimed a record 1,272 new blesseds and 452 new saintsfor veneration by Roman Catholics. On Sunday (Oct. 21), he will for thefirst time beatify a husband and wife in a ceremony honoring the role ofthe family within the church.