Pope John Paul II has reaffirmed the traditional rule of celibacy for priests in the Roman or Latin Church.

Meeting with the 2,000 priests of Rome, the pope said that their main duty is "to more effectively illumine our brothers and sisters in the world."

Priests could do this, he said, only through a style of life appropriate to the priestly calling. "For this reason, our priesthood must be pure and expressive," he said, adding that celibacy expresses the evangelical ideal of freely renouncing sex "for the sake of God's reign."

The pope told the priests that "we are necessary to people. We are immensely necessary, and not just parttime workers, like clerks. We are necessary as those who give witness and awaken in others the need to give witness. And if sometimes it seems as if we are not necessary, this means we must begin to give clearer testimony and be aware of how much the world of today needs our priestly witness."

In addition to endorsing priestly celibacy, Pope John Paul criticized priests who are overly preoccupied with wordly affairs and those who have abandoned traditional clerical dress. "Don't let us delude ourselves into believing that we are serving the gospel," he said, "if we try to dilute our priestly charisma through an exaggerated interest in the wide field of temporal problems, or if we desire to laicize' our way of living and behaving, or if we erase the outward signs of our priestly vocation.

"We must conserve the sense of our unique vocation and such uniqueness must express itself also in our exterior appearance. We must not be ashamed of this! Yes, we are in the world, but we are not of the world," he said.

The pope said he felt his experience as archbishop of Krakow would help him in his new diocese, and that at least some of the problems in Roman churches would be the same as those he found in Poland.

"I am very conscious," he said, "of what evangelization and pastoral activity mean in a city whose historic center is full of depopulated churches, while new quarters and suburbs grow, often struggling for new churches, new parishes, and other fundamental conditions for evangelization."

Pope John Paul said that as archbishop of Krakow he had enjoyed his visits to parishes and hoped to be able "to continue these here as well, in order to get to know your problems and those of the parishes."