A world is made by making a world version. So, according to Goodman, the making of a world version is what has to be understood. Carnap’s Aufbau, as already mentioned, presents a world version, the systems in A Study of Qualities and The Structure of Appearance are world versions, and so are scientific theories. The heliocentric and geocentric worldviews are relatively primitive world versions, while Einstein’s theory of general relativity is a more sophisticated one. World versions do not have to be constructed in a formal language, though; indeed, they do not need to be in a language, formal or informal, at all. The symbol systems used in the arts—such as in painting, for instance—can be used in the process of worldmaking too. It is in this sense that philosophy, science, and art are all epistemically significant; they all contribute to our understanding; they all help to create worlds.