From Alexandre Borovik's new book
Mathematics Under the Microscope
  (American Mathematical Society, 2010)–

http://www.log24.com/log/pix10/100214-Example.gif

Related material:

Finite Geometry and Physical Space
(Good Friday, 2009)

This kindergarten-level discussion of
the simple group of order 168
also illustrates Thoreau's advice:
"Simplicity, simplicity, simplicity!"