VATICAN CITY – They packed St. Peter’s Square when he was named the new pope, and they came again by the thousands to see him off.

On the eve of his retirement as head of the world’s 1.1 billion Roman Catholics, Pope Benedict XVI recalled the joy and burden of leadership Wednesday at a final general audience on which cheering devotees and a late-winter sun both smiled warmly. The eight years of his papacy, Benedict told the crowd, had been a grand journey, sometimes smooth, sometimes turbulent, but always steered by God.

“The Lord did not let us founder. … This has been a certainty that nothing can obscure,” the pontiff said, abandoning his usual practice of preaching a homily in favor of an uncharacteristically personal last address.

On Thursday evening, Benedict is set to go down in history as the first pope in 600 years to relinquish his office while still alive. He acknowledged again that his decision to step down because of failing health was a grave and novel one, but declared that he felt “a deep serenity in my soul.”

“To love the church means also to have the courage to make difficult and painful choices, keeping sight of the good of the church and not ourselves,” he said.

Some shouted, “Long live the pope!” Others held aloft banners with the word “Grazie,” or “thanks” in Italian, which fluttered next to national flags belonging to pilgrims who converged on the imposing colonnaded piazza from all parts of the world.

It was clear that, for many in the crowd of more than 100,000, nothing in Benedict’s papacy has become him quite like the leaving of it.

“It shows such humility to come down from a great level,” said Nisha Antony, a nun from India. “Have you ever seen a politician give up a high seat?”

Benedict, 85, looked frail. His voice was hoarse but did not waver when he delivered his remarks, responded to tributes in various languages, sang the Lord’s Prayer in Latin and gave a final blessing.

On the steps with the pope were about 70 cardinals, the “princes” of the church, more than 100 of whom will assemble in the coming weeks to select his successor.