The Structure of Appearance is perhaps Goodman’s main work, although it is less widely known than, for example, Languages of Art. It is, in fact, a heavily revised version of Goodman’s Ph.D. thesis, A Study of Qualities. SA is a constitutional system, which, just like Rudolf Carnap’s Der logische Aufbau der Welt, shows how from a basis of primitive objects and a basic relation between those objects all other objects can be obtained by definitions alone. We commented above already on the anti-foundationalist nature of both Carnap’s and Goodman’s constitutional systems. For them, the point of carrying out such a construction was not to provide a foundationalist reduction to some privileged basis (of experience or ontology), but rather to study the nature and logic of constitutional systems as such. In this sense, Goodman’s interest in other “world versions”, such as the languages of art, should be seen as a continuation of his project in SA.