Just exactly how Plato believed that the "nous" of people lets them come to understand things in any way that improves upon sense perception and the kind of thinking which animals have, is a subject of long running discussion and debate. On the one hand, in the "Republic" Plato's Socrates, in the Analogy of the sun and Allegory of the Cave describes people as being able to perceive more clearly because of something from outside themselves, something like when the sun shines, helping eyesight. The source of this illumination for the intellect is referred to as the Form of the Good. On the other hand, in the "Meno" for example, Plato's Socrates explains the theory of "anamnesis" whereby people are born with ideas already in their soul, which they somehow remember from previous lives. Both theories were to become highly influential.