Robin Williams, who passed away on Monday, was agile, versatile, quick-witted and almost overwhelmingly boisterous. Energy seemed to flow from everywhere else into him and then back out again in a million tiny, disparate fragments. Even at his most serious, he seemed incapable of turning off the parts of himself that might come across as obnoxious or excessive in the wrong directorial hands. As a performer, he was like a rubber band perpetually on the brink of snapping. Last night, we learned what we already knew but couldn’t bring ourselves to talk about: that metaphor applied to his life as well as his art.