Buoyed by his characteristically soaring spirit, the surging crowd around him and a pair of canes, Pete Seeger walked through the streets of Manhattan leading an Occupy Movement protest in 2011.

Though he would later admit the attention embarrassed him, the moment brought back many feelings and memories as he instructed yet another generation of young people how to effect change through song and determination — as he had done over the last seven decades as a history-sifting singer and ever-so-gentle rabble-rouser.

"Be wary of great leaders," he told The Associated Press two days after the march. "Hope that there are many, many small leaders."...