Gaylord Nelson, former Senator from Wisconsin, founder of Earth Day, and tireless environmental activist, has died at the age of 89. When Clinton awarded him a Presidential Medal of Freedom in 1995, the proclamation read: "As the father of Earth Day, he is the grandfather of all that grew out of that event: the Environmental Protection Act, the Clean Air Act, the Clean Water Act, the Safe Drinking Water Act." I encountered him once as a child, then more recently when I asked him to take part in a conceptual art project, which he gamely did. Truly a great American. Rest in peace.