Follow coverage of the honors at CNN's White House blog, The 1600 Report.

Washington (CNN) -- President Barack Obama paid tribute to "the best of who we are and who we aspire to be" in awarding America's highest civilian honor Tuesday to 15 people, including former President George H.W. Bush, poet Maya Angelou, baseball slugger Stan Musial and cellist Yo-Yo Ma.

At a White House ceremony attended by most of the honorees, Obama spoke of why each was receiving the Presidential Medal of Freedom, which the White House said is "presented to individuals who have made especially meritorious contributions to the security or national interests of the United States, to world peace, or to cultural or other significant public or private endeavors.

Other recipients of the medal included Georgia congressman and civil rights leader John Lewis; Natural Resources Defense Council co-founder John Adams; German Chancellor Angela Merkel; investor Warren Buffett; artist Jasper Johns; Holocaust survivor Gerda Weissmann Klein; humanitarian activist Tom Little, who was killed in Afghanistan; civil rights activist Sylvia Mendez; Boston Celtics NBA legend Bill Russell; nonprofit leader and former Ambassador Jean Kennedy Smith; and AFL-CIO chief John Sweeney.

Obama blended humor with solemn platitudes in describing the accomplishments of the honorees.

Speaking of Angelou, he said her voice "has spoken to millions, including my mother, which is why my sister is named Maya."

Of Buffett, the billionaire philanthropist, Obama called him "so thrifty that I had to give him a White House tie the last time he came to visit."

When the 6-foot-9 Russell stood up to receive his medal, Obama turned to the audience and shrugged, in reference to his earlier comment of always looking up to the winner of 11 NBA championships in 13 seasons playing with the Celtics, including two in which he also doubled as the league's first African-American coach.

After noting that Ma was a concert cellist at the age of 5, Obama drew laughs in referring to him as a "late bloomer." And clearly enjoying his chance to honor sports legends, he said Musial was "worthy of one of the greatest nicknames in sports, Stan the Man."

Bush, the nation's 41st president, had a public service career that spanned 70 years as a decorated Navy pilot in World War II, a U.S. ambassador to the United Nations, CIA director, U.S. envoy to China and vice president before winning the presidential election in 1988, Obama noted.

As he did about several of the other medal recipients, Obama cited Bush's humility and dedication, saying: "Those of you who know him, this is a gentleman, inspiring citizens to become points of light."