There’s always a lot of discussion about this one, for a number of reasons. There’s some unusual content (it was 1970 after all). From a historical standpoint it doesn’t have much value except as an artifact. From an archival one it’s problematic—the box contained so many loose pieces that it’s hard to find a complete copy. But if I could walk into this picture I’d grab a half dozen:
I’d love to know whose idea this was.