Pope Benedict XVI in his New Year's homily Sunday praised young people as key to securing a future of hope despite what he called "shadows on the horizon of today's world."

In the splendor of St. Peter's Basilica, with ambassadors to the Holy See from dozens of countries seated in the front rows, the pontiff, wearing white vestments with gold-colored trimmings, celebrated Mass on a day the Vatican dedicates to world peace.

"I would like to underline the fact that, in the face of the shadows that obscure the horizon of today's world, to assume responsibility for educating young people in knowledge of the truth, in fundamental values and virtues, is to look to the future with hope," the pontiff said.

Young people, he said, must "learn the importance and the art of peaceful coexistence, mutual respect, dialogue and understanding. Young people by their nature are open to these attitudes, but the social reality in which they grow up can lead them to think and act in the opposite way, even to be intolerant and violent," Benedict said.

But they will become "builders of peace" if properly educated, he predicted.

The 84-year-old Benedict looked tired during Mass, but his voice was strong, and he smiled and chatted briefly with families and young children who carried gifts to him during the ceremony. He seemed amused by one pacifier-sucking infant as the parents kneeled before the pope.

'Shadows' hanging over humanity

As he has for the past few months, Benedict used a wheeled platform, guided by ushers, to moved down the basilica's long aisle between entrance and main altar. The Vatican has said the device is meant to cut down on exertion, but is not employed because of any medical reason.

While citing the "shadows" hanging over humanity, the pontiff didn't mention specific conflicts or the economic crisis afflicting many countries.

But after Mass, in remarks in English from his studio window overlooking St. Peter's Square, jammed with tens of thousands of Romans, tourists and pilgrims, Benedict invited all to pray with him "earnestly for peace throughout the world, for reconciliation and forgiveness in areas of conflict, and for a more just and equitable distribution of the world's resources."

Again, turning his attention to young people, Benedict said they "look today with a certain apprehension toward the future," with their concerns including "the difficulty in starting a family and finding a stable job."

Italy's president, whose country is seeking to avoid financial disaster that could worsen the euro-zone crisis, did mention the bad times in comments on Benedict's reflections.

President Giorgio Napolitano, in a statement released by the presidential palace, said he shared the pontiff's "invitation to look at 2012 with a trusting attitude, even though the sense of frustration for the crisis assailing society, the work world and the economy, is quite understandable."