"God gifted him with a keen and subtle intellect, an uncommon rhetorical skill, a knack for the dramatic gesture, a sharp wit, and an outrageous sense of humor--all of which he used in the service of preaching," Cardinal Bernard Law of Boston, a close friend of O'Connor's for the past 35 years, said in his homily.
O'Connor, 80, died Wednesday of a brain tumor.
The 3,500 mourners packed inside the church erupted in applause as pallbearers took O'Connor's casket to a crypt beneath the cathedral. Outside, hundreds of people stood eight to 10 deep on a 91-degree day to listen to the Mass over loudspeakers.
President Clinton headed the long list of dignitaries who attended the Mass for O'Connor, who came to New York in 1984 from Scranton, Pa., and was appointed in 1985 as head of the nation's third-largest archdiocese, with 2.4 million Catholics.
By virtue of its location in New York, the archdiocese is the most prominent Roman Catholic pulpit in the nation, and O'Connor was a perfect fit in its media capital, serving as Pope John Paul II's most forceful spokesman in America.
"He made this pulpit unique in the history of the Catholic Church in the United States," Law said.
The pope, through the Vatican secretary of state, Cardinal Angelo Sodano, sent his condolences to O'Connor's family. Speaking at the start of the service, Sodano--who carried O'Connor's staff into the church--sounded a theme of celebration rather than loss.
"Lord, we don't complain because you have taken him from us," Sodano told a hushed crowd inside the cathedral. "But rather we will thank you for giving him to us."
The Mass opened with a 45-minute procession of O'Connor's fellow clergy. Each passing priest gently touched the cardinal's coffin, which was draped in white linen.
Many of the priests wore special vestments that had been designed for the pope's 1995 visit to New York. Among those in attendance was Bishop Edward Egan of Bridgeport, Conn., believed to be the front-runner to replace O'Connor.
A relative of Egan's, Raymond Egan, told the New York Daily News that Egan has already been appointed to the post. "He asked us not to say anything because O'Connor was so very, very sick," he said. Egan has commented.
At the end of the service, O'Connor's dark wood casket was splashed with holy water. An honor guard carried the casket down a narrow staircase beneath the altar, where all previous archbishops of New York are buried.
A one-legged boy, propping himself up on crutches, stood clapping in the aisle as the casket went past.
O'Connor was involved in planning the funeral, picking many of the prayers and songs, including the recessional hymn, "Lift High the Cross," which was performed when O'Connor was installed as head of the archdiocese.
During the previous four days, tens of thousands of New Yorkers visited O'Connor's open casket to pay their respects.
Among those at the funeral and invitation-only Mass were Clinton and his wife, Hillary; former President Bush; presidential candidates Al Gore and George W. Bush; U.N. Secretary General Kofi Annan; Sens. Daniel Patrick Moynihan and Charles Schumer; Gov. George Pataki; Mayor Rudolph Giuliani; and 15 cardinals from the Vatican, the United States, and four other countries. Giuliani greeted the guests and shook hands with Mrs. Clinton, his rival in a bitter Senate race.
There were also those whose lives the cardinal had touched. Rep. Carolyn McCarthy was a Long Island housewife in 1993 when her husband was killed and her son critically wounded by a gunman on the Long Island Railroad.
The cardinal sent her a letter offering his sympathy but promising the shootings would change the path of her life. McCarthy was later elected to Congress as a strong advocate of gun control.
"That's what made him a great man," she said. "He always reached out to ordinary people. It didn't matter what religion you were. He was truly a shepherd to all of us."
O'Connor's coffin was placed near that of Pierre Toussaint, a 19th-century Haitian whose cause for sainthood was supported by O'Connor. That portion of the ceremony was private, attended by only O'Connor's relatives and a small group of church officials.
During his years at the helm of the nation's most prominent Catholic pulpit, O'Connor placed himself at the center of some of the country's most heated debates, angering many with his staunch support of the Catholic Church's positions on abortion and homosexuality even as he charmed many critics with his warm wit.
"He'll be greatly missed," said Leo Gualtieri of Queens, standing on the steps of the cathedral. "We hope the next cardinal will follow in his footsteps."