In Union Square, peace signs and messages for tolerance proliferated around the makeshift cement monument, erected next to the towering statue of George Washington astride a war mount; reprinted articles from renowned academics Howard Zinn and Edward Said hung next to squadrons of miniature flags.

“Grief is a great excuse for horrible atrocities,” said Corthron.

“The American people have different voices, but what we’re getting from the mainstream media is so monolithic, and it all supports war.”

Others chose to forgo political discussions to concentrate on psychological healing. Nikki Boroni, a musician from Park Slope, Brooklyn, crouched on the Union Square steps in front of a sprawling series of messages, which passersby had scribbled on the ground with pastel sidewalk chalk.

“I came down to see if I could help someone who needed emotional support,” she said, staring at a queue of taxis stopped on Broadway. “But there’s just a huge pain in my heart.”

—Staff writer Mandy H. Hu can be reached at mhu@fas.harvard.edu