Recently, there's been a lot of talk about change. Most of it is directed toward the future; I've been thinking about the past. Heading to my Cambridge home one night back in the 60s, I faced a line of police in battle gear: helmets, shields, tear gas and guns. They were lined up across Mass Ave to prevent a mob of rioters from going toward Boston. It was at the height of the race riots all over the country. People were killed, buildings burned and stores looted. Last night, a black man became president-elect. This country has come a long way.