In the third book of De Anima, entitled De Intellectu, Philoponus analyzes the doctrine of the intellect. The author (Philoponus or pseudo-Philoponus?) sets the theory on the role and functioning of the active intellect. On one hand, there is the active intellect, and on the other, the idea of perception awareness or how we are aware that we are perceiving. In other words, in this reflective philosophy, there is a rationalist conclusion which emphasizes a relation between self and truth which leads to the discussion of the nature of knowledge.