Chris, this is a great take, thanks! Visiting the origins of the system doesn't fit into my current interests, but I'm very happy to know more about them.

I gave a mini-lecture to my students last night about this system; really it's more about the idea of networking your ideas over anything else, isn't it? My students, who are all working on creative nonfiction projects, were so relieved to have someplace to put and process all the things they inevitably flag in the books they read.