Plato

Plato

Plato , was a Classical Greek philosopher, mathematician, student of Socrates, writer of philosophical dialogues, and founder of the Academy in Athens, the first institution of higher learning in the Western world. Along with his mentor, Socrates, and his student, Aristotle, Plato helped to lay the...

, in The Republic (507b-509c [book VI]) , uses the sun as a metaphor

Metaphor

A metaphor is a literary figure of speech that uses an image, story or tangible thing to represent a less tangible thing or some intangible quality or idea; e.g., "Her eyes were glistening jewels." Metaphor may also be used for any rhetorical figures of speech that achieve their effects via...

 for the source of "illumination", arguably intellectual illumination, which he held to be The Form of the Good

The Form of the Good

Plato describes "The Form of the Good" in his dialogue, the Republic, speaking through the character of Socrates. The Sun is described in a simile as the child or offspring of the Form of the Good , in that, like the sun which makes physical objects visible and generates life on earth, the Good...

, which is sometimes interpreted as Plato's notion of God

God

God is the English name given to a singular being in theistic and deistic religions who is either the sole deity in monotheism, or a single deity in polytheism....

. The metaphor is about the nature of ultimate reality

Reality

In philosophy, reality is the state of things as they actually exist, rather than as they may appear or might be imagined. In a wider definition, reality includes everything that is and has been, whether or not it is observable or comprehensible...

 and how knowledge is acquired concerning it. Socrates

Socrates

Socrates was a classical Greek Athenian philosopher. Credited as one of the founders of Western philosophy, he is an enigmatic figure known chiefly through the accounts of later classical writers, especially the writings of his students Plato and Xenophon, and the plays of his contemporary ...

 is the speaker of The Republic, but it is generally believed that the thoughts expressed are Plato's.

The eye, Plato says, is unusual among the sense organs in that it needs a medium, namely light

Light

Light or visible light is electromagnetic radiation that is visible to the human eye, and is responsible for the sense of sight. Visible light has wavelength in a range from about 380 nanometres to about 740 nm, with a frequency range of about 405 THz to 790 THz...

, in order to operate. The strongest and best source of light is the sun; with it, objects can be discerned clearly. Analogous things, he writes, can be said of intelligible objects (i.e., the fixed and eternal forms that are the ultimate objects of scientific and philosophical study):

When [the soul] is firmly fixed on the domain where truth and reality shine resplendent it apprehends and knows them and appears to possess reason, but when it inclines to that region which is mingled with darkness, the world of becoming and passing away, it opines only and its edge is blunted, and it shifts its opinions hither and thither, and again seems as if it lacked reason. (The Republic bk. VI, 508d; trans. Paul Shorey

Paul Shorey

Paul Shorey, Ph.D., LL.D., Litt.D. was an American classical scholar, born at Davenport, Iowa After graduating from Harvard in 1878 he studied in Europe at Leipzig, Bonn, Athens, and Munich . He was a professor at several institutions from 1885 onward...

)

By "the world of becoming and passing away" Plato means the familiar visual or perceptual world we see around us. Thus if we attempt to understand why things are as they are, and what general categories can be used to understand various particulars around us, without reference to any forms (universal

Universal (metaphysics)

In metaphysics, a universal is what particular things have in common, namely characteristics or qualities. In other words, universals are repeatable or recurrent entities that can be instantiated or exemplified by many particular things. For example, suppose there are two chairs in a room, each of...

s), we will fail completely, as if [we] lacked reason

Reason

Reason is a term that refers to the capacity human beings have to make sense of things, to establish and verify facts, and to change or justify practices, institutions, and beliefs. It is closely associated with such characteristically human activities as philosophy, science, language, ...

. By contrast, "the domain where truth and reality shine resplendent" is none other than Plato's world of forms--illuminated by the highest of the forms, that of the Good. Since true being resides in the world of the forms, we must direct our intellects there to have knowledge, in Plato's view; otherwise, we are stuck with mere opinion of what may be likened to passing shadows.

Plato also says the sun and the Good ("the object of knowledge") are both sources of "generation":

The sun ... not only furnishes to those that see the power of visibility but it also provides for their generation and growth and nurture though it is not itself generation. ... In like manner, then ... the objects of knowledge not only receive from the presence of the good their being known, but their very existence and essence is derived to them from it, though the good itself is not essence but still transcends essence in dignity and surpassing power. (509b)

This is one of the passages that leads some to infer that the Good is, for Plato, God, though there is some dispute about this point. Many modern readers will find it puzzling that one and the same thing is called the Good, the source of being (the being of the forms, at least), something that (somehow) sheds light on all other forms, and a universal. Indeed, exactly how it is Plato thinks "very existence and essence is derived to [the forms] from" the Good is a matter of considerable interpretive difficulty.

Incidentally, the metaphor of the sun exemplifies a traditional interrelation between metaphysics

Metaphysics

Metaphysics is a branch of philosophy concerned with explaining the fundamental nature of being and the world, although the term is not easily defined. Traditionally, metaphysics attempts to answer two basic questions in the broadest possible terms:...

 and epistemology: interpretations of fundamental existence create - and are created by - ways of knowing. It also neatly sums up two views for which Plato is well-known: his rationalism

Rationalism

In epistemology and in its modern sense, rationalism is "any view appealing to reason as a source of knowledge or justification" . In more technical terms, it is a method or a theory "in which the criterion of the truth is not sensory but intellectual and deductive"...

 and his realism

Platonic realism

Platonic realism is a philosophical term usually used to refer to the idea of realism regarding the existence of universals or abstract objects after the Greek philosopher Plato , a student of Socrates. As universals were considered by Plato to be ideal forms, this stance is confusingly also called...

 (about universals).

Plato goes on to describe the levels of reality and knowledge with the device of the so-called "divided line" (509d-513e). Immediately afterward, at the beginning of Book VII (Benjamin Jowett

Benjamin Jowett

Benjamin Jowett was renowned as an influential tutor and administrative reformer in the University of Oxford, a theologian and translator of Plato. He was Master of Balliol College, Oxford.-Early career:...

 trans.), the same doctrine is elaborated in the famous allegory of the cave (514a-520a).