By Jan Repa
Europe analyst, BBC News
The pontiff presided over the summit on the issue
A meeting of senior Vatican officials called by Pope Benedict XVI has reaffirmed the Catholic Church's commitment to priestly celibacy.
A growing number of Catholic priests have expressed a desire to marry.
There are also men who have ceased being active priests in order to marry - but who now want to return to their vocation.
But the Catholic Church forbids most of its priests from marrying or entering into sexual relationships.
About one in seven Catholic priests are estimated to have left in order to marry.
The average age of a Catholic priest is now over 60 - and the numbers retiring are not being made good by new recruits.
Last year, a Vatican conference of bishops rejected what a minority there felt to be the obvious answer - let priests marry and have a "normal" family life.
After all, as Benedict XVI himself has pointed out, priestly celibacy is not a matter of Catholic doctrine - but of Church discipline.
Not so simple, say opponents of change.
After all, churches which do have a married clergy have also experienced a decline in vocations - at least in Christianity's old heartland, Europe.
It was in 1139 that celibacy actually became mandatory for Catholic priests of the Western or "Latin" rite.
Eastern-rite Catholics - former Orthodox Christians who at one time or another recognised the leadership of the Pope - retain a married priesthood.
Former Anglican ministers, who have joined the Catholic Church in recent years, and who were married before, continue to be so.
But as the writings of various "Church fathers" testify, even in the early Christian centuries, celibacy was considered a "more noble state" than marriage.
Saint Jerome, ministering to a coterie of aristocratic ladies in late 4th Century Rome, tried to impressed upon them the idea that widows should not remarry - but should, instead, distribute their inheritance among various good causes.
Catholic celibacy has been justified on pragmatic grounds.
A priest who is not emotionally or financially tied to a family, it is said, can engage himself more fully in the service of his flock.
Celibacy has also been seen as an insurance against nepotism - not that that seems to have deterred popes and prelates in the past from bestowing perks and privileges on various nephews and bastard children.
But the debate over celibacy has also been fuelled by deeper philosophical and doctrinal considerations.
On the one hand, Catholics are supposed to believe that the world was created by God, and that its pleasures, including good food and sex, are there to be enjoyed in their appropriate context.
Excessive contempt for the physical aspects of life has long been held to smack of "Manichaeism" - the heretical notion that while God created the world of spirit, the physical world is the creation of a rival, evil being.
But Catholicism also maintains that the world exists in a corrupted state - and that human destiny is fulfilled elsewhere.
So celibacy becomes a symbol of a person's commitment to that higher reality.
Some 19th and early 20th Century European thinkers even claimed that Christianity was a rebellion against Judaism's supposedly "world-bound" view of human happiness, prompted by the ancient Greeks' "tragic" vision of earthy life.
Catholicism is not alone in promoting celibacy.
In the Orthodox churches, while ordinary priests are usually married, bishops can only be appointed from among celibate monks or widower priests.
In ancient Rome, the Vestal Virgins - guardians of the "eternal flame" or symbolic "hearth" of the city - took a vow of celibacy, the breaking of which was theoretically punishable by being buried alive.
A number of Hindu and Buddhist groups practise celibacy as a way of self-purification and renunciation of the world of "illusion".
However, in the consistency with which it applies the principle, the Catholic Church probably has no equal among the major religions.