For some time I've made paintings that reflect a common theme throughout the work, an image or shape in the painting like a visual motif that appears in different forms throughout it. I called these symphonic paintings, but in the past year or two I've been focusing more consciously on the idea of visual art that uses musical symphonic forms (such as the sonata-rondo form used in classical music). I compose music too, and much of my work in other media (eg. writing, and computer programming) is emotionally and structurally related on a deeper level. The concept of an defined structure in visual art seems to be lacking.
I think this is an essential progression. Most artworks use structured forms, from small scale works like poems, to music symphonies or films. Some classical paintings have degrees of form, such as using the golden section, or a triptych arrangement (these were initially altar pieces, and so partly defined by function, but some modern artists like Francis Bacon developed this form in a secular way) but these are for the most part exceptions, and structural forms are largely absent from visual art.
Structure exists in artforms because it aids communication between artist and viewer. In writing, we use punctuation, sentences, paragraphs, and chapters for this reason. This is structure. Classical music is an essentially abstract form, and the structure helps unify what could be random or nonsensical arrangement of notes into something meaningful, creating comprehensible narrative.
Much of visual art lacks these structures, or relies on third party curation to develop them. A painting exhibition might be arranged so that it is viewed in one particular order, with a theme or grouping. This is structure, but it can be imposed by a curator at whim. For many exhibitions the artist arranges the work, but this can be seen as a separate process. The arrangement isn't always seen as the artwork itself, when this is vital; and of course the paintings on display should reflect the structure and the structure reflect the painting content.
The rules of form
1. An art installation should be structured and feature several movements, to be experienced in order, that grant it a temporal quality. Life exists in time, and visual art needs a temporal quality to represent feelings accurately. Reliance on chance or psychology or opinion for order is not sufficient. This is necessary because a complex narrative requires a complex mix of emotions and ideas, and the artist must be able to guide the viewer in the intended way to communicate accurately.
2. A structure must be unified with a theme. A theme forms common thread that pulls each separate part towards the whole, to create one singular work. An artwork on this scale is not an arbitrary segment on the line of infinite time, but a unified entity with start, middle and end, all of which together form one concept. A theme is needed to hold together the disparate parts of the structure. Variety occurs as variation of a single fundamental idea.
These are the essential rules and can apply to any art from, from poetry and music to visual art, but temporality is usually lacking in visual art. Feelings of structure, order, grace, and beauty are essential components of any artform too, but sometimes for emotional effect these can be broken. Breaking the temporal or global thematic aspects however will only ever destroy an idea and hamper communication between artist and viewer and always dilute an idea, reduce its contrast and intensity.