Having an appreciation for the subject, their students and what the subject can offer their students has both cognitive and emotional dimensions for teachers. This paper uses empirical data to explore the efficacy of a Deweyan inspired framework called "Aesthetic Understanding" to scrutinise relationships between teacher knowledge, identity and passion. The paper uses case study data of three teachers of maths and/or science generated from a video study to illustrate the relationships between the three elements of Aesthetic Understanding. The need to value the aesthetic dimensions of teaching when examining the subject-specific nature of secondary teaching is discussed. (Contains 2 tables.)