This tutoria explores symmetry as an element of composition.
Source: Image of Starry Night, Vincent van Gogh, Public Domain, http://en.wikipedia.org/wiki/File:Van_Gogh_-_Starry_Night_-_Google_Art_Project.jpg; Image of Visioni Simultanee, Umberto Boccioni, Public Domain, http://en.wikipedia.org/wiki/File:Umberto_Boccioni_-_Visioni_simultanee.jpg
Lack of equivalence or similarity between parts.
An imaginary line that divides an object.
When elements of a composition carry equal weight, or create harmony. A composition can be asymmetrical and balanced at the same time.
When two halves of something are exactly the same.
The illusion of movement in a composition.
The quality of having exactly similar parts facing each other across an axis.