“The sun illuminates, bestowing the ability to be seen by the eye with its light, as goodness illumines the intelligible with truth.”
This quote exemplifies the divide between the two worlds which make up Plato’s metaphysics: the intelligible realm and the visible realm. In Book VII, Socrates uses the metaphor of the sun to explain his view on Goodness and the Divided Line: the idea that the world is divided into the intelligible world (episteme) and the visible world (doxa). While the sun gives people the faculty of sight – giving us the power of seeing to the eye – and is the constant source of growth and light, the ideas formed in its realm (ie. the physical world) are only dull and shifting.
This is in striking contrast to the intelligible realm where goodness acts as the sun, but instead of giving people the faculty of sight under its illumination, it gives people the power of knowing to the mind. Essentially, the sun is a metaphor for the nature of reality and knowledge concerning it. The Good, as it gives rise to the true beings of the forms, is the source of all values: truth, justice, beauty and equality. Thus, the Good gives meaning and purpose to life. However, it is important to note that while the sun is accessible to all peoples in the Republic (ie. both sight-lovers and truth-lovers), only those with the capacity to use reason (ie. truth-lovers/philosophers) can access the Good. This is why the state needs a Philosopher King as the ruler because, only then, can values such as justice, equality and truth be accessed.
“This then, at last, Glaucon,” I said, “is the very law which dialectics recites, the strain which it executes, of which, though it belongs to the intelligible may see an imitation in the progress of the faculty of vision; as we described its endeavour to look at living things themselves and finally at the sun.”
This quote taken from a dialectic between Glauon and Socrates in The Republic Book VII firstly describes Plato’s Divided Line: an epistemological line that delineates the division between the intelligible realm (episteme) and the visible realm (doxa). In The Republic, it is argued that only those with the capacity and ability to use reason (ie. they are able to overcome spirit and appetite) would be able to access the World of Forms and, therefore, Goodness and subsequent values. This higher level of knowledge could be accessed through the exertion of intelligence which is said to be accomplished by primarily engaging in dialectics and mathematical reasoning – these areas of reasoning are not only referred to as activities to access the intelligible world, but also are compared to looking at the sun. Thus, Socrates transitions from the Divided Line to the metaphor of the Sun.
By comparing the ascension of the tripartite soul into the intelligible realm to the allegory of the cave (ie. the journey of our endeavour to finally look at the sun), Plato demonstrates his idea of the Perfect Form: Good. The sun creates life and lets us see while the Good is the source of all values and gives meaning to the life given to us by the sun. Furthermore, this comparison strengthens the Divided Line by indicating explicit checkpoints on the line, making it easier for us to understand the journey of the soul into the intelligible world. Looking at shadows, the fire and the reflection of the sun are events in Plato’s allegory of the Cave which can be used to demonstrate stages in the Divided Line: all of these events are in the visible realm as one is not using their reason the partake in said activities (physical things and shadows are part of doxa). “Finally at the sun” shows the final stage in the ascension of the soul and the higher point of the Divided Line: looking at the sun is equivalent to accessing the Good (forms are part of the episteme).