This volume presents texts, translations, and studies of four works of Greek political theory from the time of the Roman Empire. It is built around Themistius' Letter to Julian, a work of political advice and praise dating to the middle of the fourth century, which survives in a complete form only in Arabic translation. Themistius' Letter to Julian cannot be studied aside from Julian's own Letter to Themistius on the responsibilities of power, and this is the second major text treated here. To set the scene for these works I shall discuss a more standard political letter of the 340s or 350s, Sopater's Letter to Himerius, on his brother Himerius' responsibilities as a new governor. Finally, in the Appendix I shall complement the Letter to Julian by examining the only other genuine Greek treatise of political thought and advice to have been translated into Arabic, the Letter of Aristotle to Alexander, which appears to date to the period of the High Roman Empire and is wholly lost in Greek. Te studies around these four works touch on politics and political thinking in general but are not in any way designed to constitute a history of Greek political literature in the Roman period. Te focus is rather on the texts at hand and particularly on aspects of the career of Temistius and his relationship with Julian.