Summertime, and the livin's easy. And, of course, the movie theaters are positively glutted with quiet, meditative documentaries about things like sheep herding and our changing place in the natural world. There's Sweet Grass. ..and...well...I guess that's just about it, really. Sweet Grass does concern itself with a ritual that is not only passing but is, apparently, done gone. Captions at the end of this lovely documentary tell us that sheep have been taken out to pasture on public lands, like the Absaroka-Beartooth mountains of Montana, where much of the action (or inaction) in Sweet Grass occurs, since the late 19th-century. But the drives filmed in 2001-2003 were the last, though we are not told why the practice ended. A couple of additional statements about the context and history involved might have been useful. There is an acknowledgement to the Allested family and their ranch, but nothing to tell us ...