The main topic of this essay is the relation between philosophy and aesthetics as considered by the American philosopher Stephen C. Pepper (1891-1972). The essay has two parts. The first presents the thought-provoking theory of metaphysics (or metaphilosophy), which anticipated many important philosophical topics of the second half of the twentieth century, such as the metaphor in philosophy, the dynamic notion of structure, and the pluralistic conception of knowledge. Special attention is paid here to the core of Pepper's approach, the 'root metaphor' theory. The second part examines the application of Pepper's 'world hypotheses' to the field of aesthetics. The essay concludes by pointing out a gap in Pepper's argumentation, and by suggesting the creative development of this gap on the basis of Pepper's theory.