On how the command line is to a Unix weenie like the keyboard to a pianist "I call this class of interface 'mastery interfaces', and they are curious because they are amazingly unusable to beginners and effortlessly usable to 'experts'. This characteristic creates something of an odd social dynamic amongst the userbase. The experts can barely (if at all) re-acquaint themselves with the frustrations that newbies face, and thus have very few (and skewed) insights on how to make the system more broadly usable."