OVER SIX DECADES ago, the election of John F. Kennedy inspired a generation to believe that public service is one of the highest callings in democracy. One of those people was the young son of a milk truck driver from Malden, future US Sen. Ed Markey. As Markey would later recount, “That became a moment of great change in our country. It was no longer about the past; it was about the future and what we could do to make a difference in our world.…