Stern's had a great run. And it's impossible to have the same crazy energy at 60 or 70 that you might've had at 25. I recently looked up old video (> 40 years ago) of Jay Leno guesting on David Letterman's original show. Hysterical, but, like Stern, they're different people now. Stern always has been obviously intelligent, and good for him to go out on his own terms, with an authentic voice.