The arrow of progress in human-computer interfaces has pointed toward steadily simpler interaction. Most people have no idea what a computer is capable of doing, much less how to make the computer do it. So the dual challenge has been to present the user with the available functionality and then make it as simple as possible to put that functionality into use. Thus, the modern smartphone. The command line is in a sense a much simpler interface, but absent a cumbersome series of menus it requires the user to know what can be done. (Touch has an analogous mode with complex gestures, but few people go beyond swipe and tap.) Even if we have thought-directed cursors, that only addresses half of the interface problem. Users still need to know what their options are, and there is no corresponding "thought-display" to go along with the thought-mouse.