This was a week of endings. It kicked off with the Mad Men finale, which ended [SPOILER ALERT] with Don Draper meditating on a hilltop, just before we see the famous, "I'd like to teach the world to sing," Coke ad from 1971. Did Don create it? The series is over, but the debate lives on. Next, David Letterman -- after 33 years of smart, stupid, silly, absurd, cool, game-changing comedy -- signed off with a pitch-perfect finale, and a sincere, "Thank you and goodnight." Less bittersweet was Jeb Bush continuing to say goodbye to his senses, following up his Iraq debacle by claiming that it's "arrogant" to say there's a scientific consensus that climate change is man-made. No, what's truly arrogant is denying future generations a livable planet. Continue down this road, and the earth will say goodbye to us all. Now there's an unambiguous finale.