Thirty Nobel Peace Prize winners, scientists, economists, mayors, doctors, managers, workers, sports champions and ordinary citizens gathered at the Vatican May 10-11 for the second World Meeting on Human Fraternity, a conference organized by the Fratelli Tutti Foundation to discuss ways of promoting human fraternity in fields including the environment, education, business, agriculture, media and health.

Cardinal Mauro Gambetti, president of the foundation, introduced the conference's first discussion, which focused on promoting peace and featured seven Nobel Peace Prize winners.

Opening the roundtable discussion, Cardinal Pietro Parolin, Vatican secretary of state, said that when people disrespect peace and wage war, "they set themselves in a direction diametrically opposed to creation and, by killing their fellow human beings, they not only assault the dignity of others but their own as well."

The cardinal called for a reconsideration of the concept of "just war," which he said is "highly problematic" in an age of advanced weapons that can produce "an unlimited number of civilian causalities."

"We can safely say that all wars, by the mere fact that they contradict human dignity itself, are dynamics not intended by their nature to solve problems, but rather to exacerbate them," he said.

Muhammad Yunus, a Bangladeshi social entrepreneur and 2006 Nobel Peace Prize winner, said that weapons themselves are not the primary threat to peace in the world but rather the way that humanity thinks about itself.

"We have to rediscover ourselves as human beings with human value," he said, which entails restructuring society to achieve "a civilization of three zeros: zero global warming, zero wealth concentration and zero unemployment."

Yunus noted in particular the problem of today's "profit-centric" civilization, which is built to produce "job seekers" rather than creative individuals who are capable of changing the world.

Society, he said, is "based on maximization of profit, accumulation is the key of civilization, and (in it) we lose all the human values in us" such as sharing among groups and caring for one another.

Bill Nelson, administrator of NASA and a former Democratic senator from Florida, highlighted how his career as an astronaut provoked a passion for human fraternity by repeatedly orbiting the earth and seeing the planet in its entirety.

"I did not see racial division, I did not see religious division, and I did not see political division. What I saw was we're all in this together as citizens of planet Earth," he said, noting that such an impression, known as the "overview effect," is common among astronauts.

While it can be difficult to unite people from different nations, Nelson said space provides a setting that can bring people together and "out of our terrestrial hatreds," citing the International Space Station as an example.

Rigoberta Menchú Tum, an Indigenous Guatemalan human rights activist and 1992 Nobel Peace Prize winner, criticized the material, social and spiritual decadence of today's society and insisted there is a need for people to "nurture our soul in order to be fully human."

Graça Machel Mandela, former first lady of both South Africa and Mozambique, reflected on the institutions created by society, "which give some the right to think they can control others, to the point where they believe they can even kill others."

"We have to accept that this is man-made, it is not God-given, it is not even in nature," she said. That means "we have the power to undo this, we have the capacity to change the logic."

The leaders were scheduled to participate in numerous other discussions and meet with Pope Francis May 11.