The aim of this third chapter is to consider Julian's Letter to Themistius and the lost letter from Ihemistius to which it was replying. I shall argue that the Letter to Ihemistius is to be dated to the early period of Julian's Caesarship and that the serious tension and misunderstanding between the two men that is evident in it reflects Julian's reaction to Themistius' misjudged congratulations on his appointment. At the end of the chapter I shall revisit Themistius' Letter to Julian and shall suggest speculatively that, while this was not a reply to Julian's onslaught, we might see it as a response which constituted a rethink on Themistius' part of what an imperial advisor was supposed to say to a ruler who was not appreciative of conventional praise. Before coming to this, I shall be moving from Julian's Letter to Themistius' general attitude towards Julian. On the evidence available to us it seems that their relationship did not recover from the assault in the Letter, and there are deliberately strong criticisms of the late emperor in some of Themistius' speeches to Jovian and Valens. I shall be examining the specific question of whether Themistius did nevertheless hold office under Julian, as the Suda records he did. It is possible that Themistius did serve, but perhaps briefly and unhappily. If that is right, the experience will have added to his later denigration of Julian.