WATERVILLE — A handful of protesters briefly interrupted a speech calling for world unity delivered by former British Prime Minister Tony Blair at Colby College’s graduation ceremony Sunday.

“The world is connected as never before, make use of it,” Blair told the class of more than 400 during the 191st commencement exercises at the college.

Blair spoke of a global future and urged students to be generous of both spirit and person, saying “compassion is as important as ambition.”

During the speech, police arrested Lawrence Reichard, 53, of Bangor on a charge of criminal trespass, and escorted several other demonstrators off the campus when they refused to stop yelling comments such as “war criminal,” Waterville police said.

Protesters carried signs saying “Code Pink,” a grassroots peace and social justice movement working to end U.S.-funded wars and to challenge global militarism, police said.

Peaceful sign-carrying demonstrators were not asked to leave, according to Ruth Jacobs, associate director of communications for the private, liberal arts college in central Maine.

“The college is all about the open exchange of ideas,” she said.

The 59-year-old Blair, the Labor Party’s longest-serving prime minister, served from 1997 to 2007. Since then, he has served as the envoy of the Quartet on the Middle East, representing the United States, Russia, the European Union and the United Nations in working with Palestinians to prepare for statehood.

In one of several lighter moments Sunday, Blair joked that the graduates live in a new, more public world of cellphones, social media and Facebook than he had.

“There was no record of my career as a rock musician,” he said. “If there had been, I wouldn’t be standing here.”

Among seven tips Blair offered students was to never stop learning, “carry on” and “have the humility always to know you can learn more.” He recalled talking with Nelson Mandela at the South African leader’s height of his power, who told him, “‘There is so much I don’t know, so much I still have to learn.’”

Blair, who has gone through a spiritual evolution since leaving office, urged students to not be closed-minded.

“An open mind is the universal spirit,” he said. “Be open to those of different faiths, cultures, races and nations.” Don’t judge others, he said. “Other people are not worse than you, they’re just different . be enriched by them.”

He talked of the growth of China, India, Africa and the Arab world and told the graduates how lucky Colby alumni are for their early opportunities in life.

Blair told them to be leaders and not followers, doers and not critics, and to have courage: “Don’t be afraid to fail, we all do; be afraid of not trying.”

“Courage is not the absence of fear, it is the overcoming of fear,” he said, recalling his own embarrassment when he became prime minister and had to kiss the queen’s hand at Buckingham Palace. He said that when he was required to brush her hand lightly as part of the ceremony: “The door opens, I go in, I see the queen, I’m so nervous, I trip over the bare carpet in front of the throne and I don’t actually kiss her hands, or brush them — I envelope them.”

Today’s world is a time of challenge and an era of unique unpredictability, “with uncertainty everywhere,” Blair said, describing a global world in which diverse cultures are growing rapidly.

He told graduates that to live in that new world, they need to have confidence, cherish friendships and family and accept diversity.

“Be optimistic, count your blessings, they are many,” Blair said. “Have a sense of purpose and a thankful heart . Be open to life and make the most of it.”