Hierachy

Datum

Symmetry

Proportion

Contrast

Rhythm

Figure Ground

Any found images courtesy of: 

http://commons.wikimedia.org/wiki/File:Whirlpool_by_lord_rosse.jpg

http://chiaralily9.deviantart.com/art/Sepia-Foggy-Background-255443119

http://www.istockphoto.com/stock-illustration-19873746-window-washer-at-work.php

http://www.colourbox.com/vector/silhouettes-of-circus-performers-acrobats-and-jugglers-vector-4367058

http://www.wellingtonwaterfront.co.nz/media_section/news_releases/news_release_archive/lighting_award.htm

http://jillsbooks.wordpress.com/2011/07/15/poetry-friday-60/girl-blowing-dandelion-silhouett/

http://123freevectors.deviantart.com/art/People-Silhoutte-Vector-102141196