Throughout “The Allegory of the Cave,” light is shown to be a literal manifestation of enlightenment or wisdom. It is only through access to some kind of light, albeit dimly reflected off a cavern wall, that the prisoners in the allegory can know anything at all of the shape of things (mention is also made of reflected sound, though Socrates does not dwell on this, preferring instead to speak in terms of the visual). Once one gains access to light more fully and by degrees, one can come to fuller knowledge and wisdom. However, the Platonic Socrates also notes that transitions from dark to light and from light to dark can be painful and disorienting, which helps him further illustrate the nature of wisdom, and its difficulties and discomforts. Light serves as an apt metaphor, providing a jumping off point for the deeper analysis that is Plato’s goal through the text.  

As mentioned in the previous section, while light symbolized enlightenment and wisdom, darkness symbolizes ignorance. The prisoners trapped in the cage only know darkness, and, because of this, they cannot know that the shadows they see are not the true forms themselves, but simply representations of them.