 With respect to art in particular and to symbolic activities in general, Goodman advocates a form of cognitivism: by using symbols we discover (indeed we build) the worlds we live in, and the interest we have in symbols—artworks amongst them—is distinctively cognitive. Indeed, to Goodman, aesthetics is but a branch of epistemology. Paintings, sculptures, musical sonatas, dance pieces, etc. are all made of symbols, which possess different functions and bear different relations with the worlds they refer to. Hence, artworks require interpretation, and interpreting them amounts to understanding what they refer to, in which way, and within which systems of rules.