Ideas alone can be works of art; they are in a chain of development that may eventually find some form. All ideas need not be made physical.
The idea part is simple but the visual perception is complex.
Formal art is essentially rational.
The idea becomes a machine that makes the art.
One usually understands the art of the past by applying the conventions of the present thus misunderstanding the art of the past.
Conceptual art is only good if the idea is good.