This paper focuses on Augustine's concept of self-knowledge or self-awareness in non-rational animals through examining the relation between external senses, internal sense and rationality. The explanation of what causes motion in non-rational living beings is quite puzzling in the case of animal's self-perception -for what reason do they move, sense or live. This motivation is also connected to the self-preservation principle, which is one of the two sources of confusion regarding self-perception in animals; the other one is the ability of internal sense or anima to perceive themselves, other animals and humans as alive -in spite of the fact that this can in no way be sensory information.