Chapter 2 begins with an overview of existing definitions of art and connects these definitions with philosophical ideas about the fundamental nature of reality – including the arts – in the form of ontologies or worldviews. It analyzes the properties of those ontologies in the context of the visual arts and concludes with the introduction of process ontology (readers who don’t like philosophy and definitions might wish to skip this chapter, or read it later once they have come to think that philosophy and definitions are not uninteresting after all).