Plato, in
The Republic (507b-509c), uses the sun as a
metaphor for the source of "illumination", arguably intellectual illumination, which he held to be
The Form of the Good, which is sometimes interpreted as Plato's notion of
God. The metaphor is about the nature of ultimate reality and how we come to know it. (
Socrates is the speaker of The Republic, but it is generally believed that the thoughts expressed are Plato's.)
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