日本では永井均の邦訳で広く読まれた20世紀哲学の名論文を原書Mortal Questionsから初めて単独の小著として刊行し、ネーゲルの最近の思考をあらわす第二論文を併録。This book is a fiftieth anniversary republication of Thomas Nagel's What Is It Like to Be a Bat?, a classic article in the philosophy of mind. Through its argument for the irreducible subjectivity of consciousness, it played an essential role in making the study of consciousness a central part of philosophy, psychology, and neuroscience. It also spurred the now flourishing scientific attention to the consciousness of non-human creatures: mammals, birds, fish, mollusks, and insects. The book also includes a second essay offering Nagel's more recent thoughts on the most promising positive response to the mind-body problem, as posed in the original essay.