The chapter, informed by the Systematicity and Understanding Theses, discusses how understanding in medicine bolsters human agency. Rejecting the initial pathocentric proposal of medicine’s aim (Pellegrino 2001; McAndrew 2019; Hershenov 2020), it advocates the Autonomy Thesis that argues medicine’s goal is not merely treating disease, but promoting health to enhance autonomy (Christman 2009). It adopts a "positive" notion of health that is more than disease absence (Venkatapuram 2013; Nordenfelt 2017) and establishes its relation with well-being and autonomy. The chapter introduces a pluralistic view of health concept difficulties through the lens of "conceptual engineering" and refutes criticisms suggesting the Autonomy Thesis’s permissiveness. The investigation is confined to "mainstream medicine" (Broadbent 2019, ch. 1) and considers the internal morality of medicine (Brody and Miller 1998; Pellegrino 2001). It strives to define a broad yet rigorous aim of medicine that applies to various branches.