But now he was enormously more sophisticated than he had been ten days ago.  He understood windows, realized that the bubble surrounding him was a window and meant for looking out of and that the changing sights he saw were indeed the cities of these people.  He understood maps and could pick out, with the help of the girls, where they were and what they were seeing on the map flowing across the lap board in front of them.  But of course he had always known about maps; he simply had not known until recently that humans knew about maps.  It had given him a twinge of happy homesickness the first time he had grokked a human map.  Sure, it was static and dead compared with the maps used by his people - but it was a map.  Mike was not disposed by nature and certainly not by training to invidious comparisons even human maps were very Martian in essence - he liked them.