In this paper I consider a problem – originally raised by Thomas Aquinas – that is a side effect of integrating Aristotle’s epistemology with Augustine’s. Thus, how can the human soul obtain knowledge of its own stable dispositions (habitus)? In a serious attempt to meet the constraints that Aristotle had placed on the possibility of human reflexive thought, Aquinas builds his answer on a distinction between actual and habitual self-knowledge. Both Matthew of Acquasparta and Roger Marston will draw on the distinction, as well as on the overall formulation of the problem, and yet – due to a stronger commitment to Augustineʼs epistemology – they will reject with different arguments Aquinas’s solution