In previous chapters of "Interpreting Kant in Education," a particular set of assumptions about mind and world has been identified for their influence on the familiar 'Kantian' picture in education, a picture that receives widespread criticism. In this fourth chapter, various understandings of familiar concepts are again discussed for the purpose of developing a more valuable reading. Continuing with the consideration of ideas about mind and world that underlie different interpretations, this chapter looks at diverse conceptions of world--nature and reality. Kant's Copernican view has been discussed in relation to traditional metaphysics and empiricism; here it is contrasted with naturalist epistemology. Versions of naturalism and materialism are considered, drawing on the work of John McDowell, Sebastian Rödl and David Bakhurst, to draw attention to different ways of conceiving what is real and natural in the world. Discussion is aimed at helping with an understanding of Kant's (non-traditional) version of idealism.