One clear-cut theme in modernist thought is the emphasis placed on the inner reality over the outer, visible reality. Psychology comes into play, blurring the line between external and internal experiences. This extreme shift in focus can be interpreted as another form of rebellion against classic notions. In literature, for instance, stories don’t have to be linear, because the mind doesn’t think in a proper chronological order. Stories don’t have to have a clear-cut ending, because they keep on going independent of the reader’s consciousness.
At the core of modernism is its defiance of society’s standards and traditions. This can manifest in as small a sphere as a family unit, or zoom out to encompass religion, government, socioeconomic hierarchy, gender and race. Conventional, predictable frameworks are rejected in favor of freedom and anarchy or of a new and completely different structure.
The theme of the grotesque is a more specific form of the rejection of norms. It takes a familiar, traditional element and warps it so that the viewer sees it as something unnatural. The grotesque manipulates the viewer’s psychology by making him uncomfortable with what is commonplace.
Technology, or at least a distilled form of it, is also part of the basic rejection of tradition that defines the modernist movement. Part of modernism involves taking a radical leap into the future, and technology is one of the simplest means of doing so. Modernist art and literature makes use of this theme by showing new modes and styles of living -- education, transportation, communication, commerce and all the minutiae of daily life -- either as their main subject or as a background to it.
Structure and geometry as a theme of modernism is partially related to technology, in that emphasis is put more on functionality and less on the decorative aspect of things. Though ornamentation and embellishments in general are taken away, a specific type of aesthetic remains in that elements are streamlined and consistent. In non-visual art forms, this manifests in the unity and flow of events and in the interrelatedness of all contributing elements.