Double Letters

A puzzling riddle

I do not spend as much time on the other three smaller boxes as I do the Appalachian Footpath Box, so it is fun for me each time I return to any of those boxes to catch up on what people are saying and to see if I notice the same things or something new. I have seen enough references to “double letters” in the Past and Future Box chapter to make me want to take a closer look at this dimension.