In "what is it like to be a bat", Nagel explores the subject of consciousness and subjective experience in non-human animals. He believes that although we can study the physical and behavioral aspects of animals, we cannot fully understand what they are like. Nagel uses bats as an example because their sonar-based perception of the world is fundamentally different from our own sensory experience. According to Nagel, consciousness is subjective and cannot be reduced to a purely physical process. He believes that any conscious experience has a unique "what it's like" aspect that is unique to the individual experiencing it. Since we can't objectively know what it's like to perceive the world as bats do, Nagel thinks our understanding of the consciousness of other animals will always be limited. Nagel's article raises important questions about the limits of our knowledge and conscious understanding, and highlights the challenges of empathizing with creatures whose experiences are fundamentally different.