Traditionally, two claims have been made about Augustinian views on self-knowledge: firstly, that according to Augustine the soul is fully transparent to itself, meaning that it has an unmediated access to its essence; secondly, that medieval Augustinians retained this unmediated access to the essence of the soul by itself, thus opting for a view alternative to authors of an Aristotelian hue for whom the soul knows itself only by means of knowing its acts. In the first part of my paper, I argue that the traditional reading of Augustine is correct with the qualification that such transparency is proper to the human mind, which means that it does not apply to the soul of non-rational animals. Sensory self-awareness in non-rational beings must be understood in the restricted sense of awareness of the state of their sense organs. In the second part of my paper, I investigate how the principle of the soul's transparency is understood by a sample of late medieval thinkers with the aim of showing that the traditional distinction between Augustinians and Aristotelians on self-knowledge is progressively blurred.