An influential doctrine of modern philosophy states that we discover what we think, perceive, or feel by turning our gaze inward to directly observe the states of our mind. The core thesis of this book is that this view is incorrect. If we want to know something about our mind, we do not need to look inward, but rather take a look at the world around us. In this sense, our own mind is transparent: not by revealing itself in an infallible introspection, but by the fact that every attempt to perceive it inevitably leads to the consideration of those matters in the external world to which we are intentionally related. Wolfgang Barz defends this idea using examples of beliefs, desires, intentions, sensory impressions, bodily sensations, and emotions.