About 100 members of John F Kennedy's family have gathered in Washington to mark the 50th anniversary of the murdered US president's inauguration.
His daughter Caroline said she had been thinking over her father's often-quoted inaugural speech on January 20 1961, in which he told the world that "the torch had been passed to a new generation of Americans" whom he challenged to "ask not what your country can do for you - ask what you can do for your country".
She said when her father proclaimed that Americans "shall pay any price, bear any burden, meet any hardship, support any friend, oppose any foe, to assure the survival and the success of liberty", he "really expanded and redefined our idea of what it means to be a citizen - that everybody has something to contribute and everybody has something to give back to this country that's given us so much".
Ms Kennedy said: "It's not just an obligation, but it's really a rewarding experience and really a belief in government and politics as a noble profession."
She joined members of her father's administration, civil rights activists, astronaut Buzz Aldrin and members of the first class of the Peace Corps - which JFK established - to mark the 35th president's legacy at the US Capitol.
Family members gathered at the Kennedy Centre for the Performing Arts on the bank of the Potomac River which stands as a living tribute to Mr Kennedy, whose White House embraced the arts. It opened three weeks of performances that will recreate moments from those "Camelot" days.
President Barack Obama, opening the concert, paid tribute to the "unfinished life" of JFK and said his inauguration and his accompanying call for Americans to serve their country still "inspires us and lights our way".
Mr Obama, who was not born until later in 1961, hailed Mr Kennedy for leading a "volatile America in this tinderbox of a world", with a steady hand, "defusing the most perilous crisis since the Cold War without firing a single shot".
He also noted JFK's work to help blacks attend their choice of college, launch the Peace Corps of goodwill ambassadors around the world and set America's sights on landing on the moon.
Earlier, speaking at a ceremony in the Capitol's rotunda, Vice President Joe Biden said JFK's cause was to bring America back "to what it should be".