“Nobody would have been shocked if, as Letterman aged, he simply tried to cling to his younger irreverence, flinging his 68-year-old self to Velcro walls, like in the old days. That’s what TV does to people who want to stay on TV, and it’s usually a cringefest. Instead, Letterman began a quiet but noticeable transformation to a broader, more open, human version of himself.”