What is a good life? What is truly important? Which path leads to happiness? Different ancient philosophical schools answer these questions in very different ways. The Stoic response is: "to live according to nature" - and for the Stoics, this primarily means "guided by reason." Consequently, the rigorous Stoicism teaches the suppression of all passions such as anger, sadness, and love. Seneca's "Moral Letters" initially present themselves as practical and relatable guides for everyday life, thus appealing to philosophical novices; however, they gradually become more dogmatic. The analysis of Seneca's literary technique, as well as the personal and critical engagement with the Stoic doctrines of goods and passions, are the core concerns of this edition.