Martin Luther made substantial use of Renaissance humanist rhetoric in his correspondence through 1518, when two events, the aftermath of the interview with Cajetan and the upcoming Leipzig Debate, impacted his professional life. This chapter takes up four significant humanist themes from the correspondence. First, there were the ever-present educational concerns. Compelled to pursue challenges from Cajetan and Eck, these were largely relegated to the back - burner. Second, there was the matter of style in the letters. Luther's use of language shifted, as he emphasized Greek vocabulary and augmented his vernacular correspondence with the princes. Renaissance humanist style and method were again apparent, albeit less frequently than before. Third, Luther's correspondence bore a serious tone. Vainglorious humanist compliments became rare. The term humanissime virtually disappeared. Fourth, Luther used various methods to defend himself against a broad range of opponents. Often resorting to an offensive posture, his letters sometimes bristled with humanist barbs and stratagems.