In general, the overall subject of art is balanced proportion and harmony.
This can be expressed in two ways:
The work of art also depends on experience (aesthetical, ethical, literary or social).
In the most modern artistic expression—at least in its consequence (so-called Abstract Art or Neoplasticism)—a maximum of expression of the idea of art is achieved.
The various movements (between A and B, principle II), including Dadaism, were developmental and intermediary stages towards a new style.