In the previous chapters of "Interpreting Kant in Education," some different understandings of Kant's key terms were contrasted in order to begin to bring a more favourable picture of Kant into view. This third chapter continues the process through a discussion of Kant's 'Copernican revolution'. Most in education will be familiar with Kant's idea that objects conform to our knowledge, but this can be understood in different ways. Typically read as a subjectivist 'mind makes nature' move, Kant is widely characterised in educational theory as a constructivist, with mind often reified as ordering and structuring the sense data of experience, or imposing meaning and principles. Here Kant's Copernican insight is considered in relation to the prevailing metaphysics of his time, emphasising his rejection of this and showing how original his thinking is. Addressing the question of just what is mind-dependent on Kant's mind-dependent view involves considering the conceptions of the relation between subject and object, mind and world, that underlie different interpretations. The idea of objective constraints is introduced to begin to emphasise the objectivity of Kant's Copernican insight, which tends to be obscured in 'mind imposes meaning' portrayals in education.