Summoning the soul of a nation, President Barack Obama on Wednesday implored Americans to honor those slain and injured in the Arizona shootings by becoming better people, telling a polarized citizenry that it is time to talk with each other "in a way that heals, not in a way wounds."

Following a hospital bedside visit with Rep. Gabrielle Giffords, the target of the assassination, he said: "She knows we're here, and she knows we love her."

Speaking at a memorial in Tucson, Arizona, Obama bluntly conceded that there is no way to know what triggered the shooting rampage that left six people dead, 13 others wounded and the nation shaken. He tried instead to leave indelible memories of the people who were gunned down and to rally the country to use the moment as a reflection on the nation's behavior and compassion.

"I believe we can be better," Obama said to a capacity crowd at the University of Arizona basketball arena _ and to countless others watching around the country. "Those who died here, those who saved lives here _ they help me believe. We may not be able to stop all evil in the world, but I know that how we treat one another is entirely up to us."