This book is a study of the literary strategies which the first professional philosophers used to market their respective disciplines. Philosophers of fourth-century BCE Athens developed the emerging genre of the "protreptic" (literally, "turning" or "converting"). Simply put, protreptic discourse uses a rhetoric of conversion that urges a young person to adopt a specific philosophy in order to live a good life. The author argues that the fourth-century philosophers used protreptic discourses to market philosophical practices and to define and legitimize a new cultural institution: the school of higher learning (the first in Western history).