Melvyn Bragg and guests discuss the insight into our relationship with the world that Immanuel Kant (1724-1804) shared in his book The Critique of Pure Reason in 1781. It was as revolutionary, in his view, as when the Polish astronomer Copernicus realised that Earth revolves around the Sun rather than the Sun around Earth. Kant's was an insight into how we understand the world around us, arguing that we can never know the world as it is, but only through the structures of our minds which shape that understanding. This idea, that the world depends on us even though we do not create it, has been one of Kant’s greatest contributions to philosophy and influences debates to this day. The image above is a portrait of Immanuel Kant by Friedrich Wilhelm Springer With Fiona Hughes Senior Lecturer in Philosophy at the University of Essex Anil Gomes Associate Professor and Fellow and Tutor in Philosophy at Trinity College, Oxford And John Callanan Senior Lecturer in Philosophy at King’s College London Producer: Simon Tillotson