The Language of Design
Art is very similar to a language and has it's own words and sentences. To understand any art object, you must understand the language of design.
The elements of art, are the 'words' of art and the visual vocabulary used by an artist. The elements of art consist of color, value, line, texture, shape, form and space. Artists use the elements of art to express their ideas.
Like any other language just having words is not enough. Carelessly placed words on a page would be of little value to anyone. Therefore, words must be carefully arranged and organized into meaningful sentences, phrases, and paragraphs so that the reader will be able to understand the writer's ideas.
The principles of art are the sentences, phrases, and paragraphs, used to organize the words, the elements, of art. The principles of art consist of balance, emphasis, harmony, variety, gradation, movement, rhythm, and proportion.
However, merely having sentences, phrases, and paragraphs that make sense isn't enough either. Like a novel, for an artwork to be successful, the novel as a whole has to make sense. Disorganized sentences, phrases, and paragraphs will make the novel feel incomplete and confuse the reader.
Unity is used to refer to the overall look and feel of an artwork. In works where unity is evident, the elements and principles work together to show harmony and completeness.