Days after a horrifying act of violence, a Democrat from Connecticut stood on the Senate floor and declared, “I hope that this brutal, senseless killing will shock the Congress into backing me in this fight to take the guns from the hands of assassins and murderers.” The senator was not Chris Murphy of Connecticut, who has become Capitol Hill’s leading voice for gun safety legislation. And the act of violence was not the kind of mass shooting that haunts our nation in the 21st century. It was 50 years ago, after the assassination of the Rev. Dr. Martin Luther King Jr., that one of Senator Murphy’s predecessors, Thomas Dodd, issued this stirring plea.

King was murdered in Memphis on April 4, 1968. That killing, together with the assassination of Robert F. Kennedy two months later, spurred the passage of the Gun Control Act that year. It was the first time since the 1930s that the federal government had passed a major gun control bill.

We are now witnessing the emergence of the most passionate movement for gun control since 1968. The country’s ordeal half a century ago illustrates that horrific episodes of gun violence do not themselves prompt legislative action; only the sustained pressure of an energized populace can do that. The students of Marjory Stoneman Douglas High School in Parkland, Fla., surely grasp this truth.

Those who organized for gun control in 1968 ultimately obtained a piece of legislation that President Lyndon Johnson admitted was “not nearly enough.” The question remains whether the eloquent and indefatigable Stoneman Douglas students, and their millions of allies across the country who will take to the streets in protest this weekend, can push legislators further.