Can anyone explain to me how to make those universal primitive mazes, starting from a plus sign with four dots, one at each corner? I saw it demonstrated by computer animation on some public television laundry-list documentary on mazes, but it went by too fast and too but of course for me to retain it all. My attempts to recreate the maze have failed, and it looked so easy and obvious.

Character names: Sue Generous. Joseph Cairo (Xp).