This is a great tutorial on all the four basic design principals. The creator has made remember the principals of design easy by calling it the C.R.A.P design principals. C.R.A.P standis for contrast, repetition, alignment and proximity.
"Graphic design contains underlying principles that govern the most important aspects of great design. These principles create the acronym C.R.A.P. which stands for contrast, repetition, alignment, and proximity." This link provides both good written examples and picture examples.
I decided to share this so everyone could be as disappointed as I was when I found out it was not the Robin Williams I was thinking of. The article has plenty of relevant points though and is worth a read.
Chapter 6, Repetition: An analysis of contrast, repetition, alignment, and proximity with examples of each in the form of website design. This shows how they all work in harmony and how they impact the design element of a website.