Harmony is agreement and accord. It is a union or blend of aesthetically compatible components in a work of art. The composition is harmonious when the interrelationships between its parts fulfill aesthetic requisites or are mutually beneficial. As a principle of design, harmony refers to a way of combining elements of art to accent their similarities and bind the parts into a whole. Harmony is often achieved through the use of repetition and simplicity. However, excessive harmony leads to monotony and boredom. Relieving this may be elements of contrast; even of dissonance.