rhythm - is another idea of opposites - sounds and silence

Visual rhythm is described as timed movement through space; an easy, connected pathway along which the eye glides through a regular arrangement of motifs. The presence of rhythm creates a fluid predictability and order in a composition. Visual rhythm may be best understood by relating it to rhythm in sound.

Rhythm depends largely upon the elements of pattern and movement to achieve its effects. The parallels between rhythm in sound/ music are very exact to the idea of rhythm in a visual composition. The difference is that the timed "beat" is sensed by the eyes rather than the ears. 

Visual rhythm can be created in a number of ways.  

Linear rhythm refers to the characteristic flow of the individual line. Accomplished artists have a recognizable manner of putting down the lines of their drawings that is a direct result of the characteristic gesture used to make those lines, which, if observed, can be seen to have a rhythm of its own. Linear rhythm is not as dependent on pattern, but is more dependent on timed movement of the viewer's eye. 

Repetition involves the use of patterning to achieve timed movement and a visual "beat". This repetition may be a clear repetition of elements in a composition, or it may be a more subtle kind of repetition that can be observed in the underlying structure of the image. 

Alternation is a specific instance of patterning in which a sequence of repeating motifs are presented in turn; (short/long; fat/thin; round/square; dark/light).   

Emphasis is also referred to as point of focus, or interruption. It marks the locations in a composition which most strongly draw the viewers attention. Usually there is a primary, or main, point of emphasis, with perhaps secondary emphases in other parts of the composition. The emphasis is usually an interruption in the fundamental pattern or movement of the viewers eye through the composition, or a break in the rhythm.

The artist or designer uses emphasis to call attention to something, or to vary the composition in order to hold the viewers interest by providing visual "surprises." 

Contrast achieves emphasis by setting the point of emphasis apart from the rest of its background. Various kinds of contrasts are possible. The use of a neutral background isolates the point of emphasis.  

Prolonged visual involvement through intricacy (contrast of detail) is a more unusual form of emphasis, not as commonly used in Euro-American design, though it is common in many other cultures. In this case, many points of emphasis are created that are to be discovered through close attention to the intricacies of the design.

Unity is the underlying principle that summarizes all of the principles and elements of design. It refers to the coherence of the whole, the sense that all of the parts are working together to achieve a common result; a harmony of all the parts.

Unity can be achieved through the effective and consistent use of any of the elements, but pattern-- that is, underlying structure-- is the most fundamental element for a strong sense of unity. Consistency of form and color are also powerful tools that can pull a composition together.