"The Marching Morons" is a look at a far future in which the world's population consists of five billion idiots and a few million geniuses – the precarious minority of the "elite" working desperately to keep things running behind the scenes. "The Marching Morons" is a direct sequel to "The Little Black Bag": it is easy to miss this, as "Bag" is set in the contemporary present while "Morons" takes place several centuries from now, and there is no character that appears in both stories. The titular black bag in the first story is actually an artifact from the time period of "The Marching Morons": a medical kit filled with self-driven instruments enabling a far-future moron to "play doctor". A future Earth similar to "The Marching Morons" – a civilization of morons protected by a small minority of hidden geniuses – is used again in the final stages of "Search the Sky".