To get an even better explanation on what the word "simple" means and what it derives from, I would recommend "Simplicity Ain't Easy" by Stuart Halloway[1]. While it is very similar to "Simple made Easy", it focuses a lot more on the etymology of the words "simple" and "complex" and how people misuse the word.

[1]: http://www.youtube.com/watch?v=cidchWg74Y4