At its Nashville premier, Ken Burns described his new documentary as an eight-year “labor of love” drawing on more than 100,000 photographs, 3,000 movies, 1,000 home movies, and 300 hours of recorded music. It could only have been done, he said, by already having made all his previous films about American experience. Country Music offers eight episodes that together exceed sixteen hours, and begins tonight, September 15, on PBS. Curt Ellison will outline a few of the complicated  historical, social, musical, financial and religious contexts of country music and its cultures, discuss keys to success for its artists, and consider distinctive ways that fans embrace it. And, of course, ask why such popular culture phenomena exist.  Service Leader: Linda Amspaugh.  Monthly Potluck will follow.