Plato and the Theory of the Forms
In the Republic, Plato creates three analogies to explain how the Theory of the Forms works. The first analogy is the analogy of the Sun. The analogy of the Sun has three separate elements: eyes, the Sun, and material objects. The connection between the eyes, the Sun, and material objects is that the Sun enables the eyes to see material objects. Eyes have the power of seeing and material objects have the power of being seen. The Sun enables eyes and material objects to perform their roles because the Sun provides light so that eyes have the ability to see material objects. The broader significance of this relationship is it illustrates how we come to know about things in the material world. Because we have perceptive apparatus, such as eyes, we are able to perceive material objects with the help of something else in the material world, such as the Sun, to enable a connection between eyes and material objects.
The Sun acts as a metaphor for the Good, eyes act as a metaphor for the mind, and material objects act as a metaphor for the Forms. Similarly, the connection between the Good, the mind and the Forms is that the Good enables the mind to know about the Forms. The mind has the power of knowing, which is analogous to the eyes having the power of seeing, and the Forms have the power of being known, which is analogous to material objects having the power of being seen. The Good provides the mental capacity for the mind to understand the Forms. This is analogous to how the Sun provides light to enable the eyes to see material objects. Without the Good, the mind would be unable to comprehend the Forms.
The Sun analogy is significant for the theory of the forms in that it illustrates how we come to know about the intelligible, or abstract, world. Just as the Sun illuminates the visible realm so that eyes can see material objects, the Good illuminates the intelligible realm so that the mind can comprehend the Forms. This analogy is supposed to tell us