This thesis examines, on a case study basis, how written texts and traditions function in the construction of a Roman philosophical identity in Seneca's Epistulae Morales, and how these moral letters operate within the shared cultural framework of Seneca and his audience. In sum, Seneca's Epistulae Morales aim to construct and legitimise a Roman philosophical identity, and to make the journey of moral progress undertaken by Seneca and the addressee Lucilius the paradigm for its wider Roman audience. The first part of the book, consisting of two chapters, discusses the central theoretical concepts and how these can be applied effectively to the study of Seneca's letters. It studies the cultural context of Seneca and his audience as well as the textual traditions to which the Epistulae Morales belong. In the second part of my thesis four letters (Ep. 11, 15, 78, 106) serve as case studies, each letter constituting one of the four chapters. The central theme in the selection of letters is the topic of the body. The theme of the body helps to bear out Seneca's construction of a cultural identity and his reinterpretation of authoritative texts and traditions as it serves as an ideological battleground characterised by disagreement and professional competition for authority on the subject. Against the background of various competing views, Seneca assesses the importance of physical exercise, chooses mental health over bodily health, and discusses the inability to change inborn characteristics scuh as blushing. This study brings out the process of cultural identity construction in the letters, drawing attention to the nature of cultural memory as inscribed in literature, as well as the interpretation of 'our own' views and values, and those of 'others'. Seneca's aim to adapt Greek (Stoic) philosophy to a Roman audience calls for the integration of different cultural backgrounds. The ambitious claims of philosophy, combined with the partly critical Roman attitude towards Greek philosophy, provide a challenging background for his project of presenting philosophy as not merely a viable, but even the most suitable, option for a member of the Roman elite. At the same time, in order to appeal to his Roman audience, Seneca takes account of the Roman cultural perspective and customises the philosophical tradition by addressing Roman concerns and by writing in Latin. In addition, Seneca capitalises on the epistolary form to give personal advice, to underline the friendly bonds between him and Lucilius, and to present a model for others that actualises a philosophical life in accordance with Roman culture. By singling out five central identities in the letters—the human, Roman, upper-class, philosophical and Stoic identity—we further define key elements of Seneca's self-presentation. In placing emphasis on the arrangement of the different themes within each letter, on how epistolary features are employed, and on how text and audience presuppose one another, the book seeks to further our understanding of these individual letters, of the Epistulae Morales as a literary and philosophical work, and of the ways in which Seneca conveys his philosophical message to his audience.