In recent years, there has been growing interest in the role of affect within education. Within this paper, the authors make a distinction between affective pedagogy, which they refer to as ways of teaching that are designed to evoke particular emotional states, and affective knowledge, which they refer to as aspects of knowledge or knowing which seem to bring forth particular emotions organically. Using explicit grammar knowledge as a test case, they explore student teachers' affective responses to learning, drawing upon interview data and observations made during a series of grammar courses. They argue that grammar learning is a potential source of pleasure, wonder and intensity. The findings provide an important counter-narrative to the prevailing discourse of grammar as dull and threatening. They also draw broader conclusions about the significance of affect in education, drawing upon affect theory and recent work on epistemic emotions.