The divided line

Plato's Divided Line
At the end of Book VI of the Republic (509D-513E), Plato describes the visible world of perceived physical objects and the images we make of them (in our minds and in our drawings, for example). The sun, he said, not only provides the visibility of the objects, but also generates them and is the source of their growth and nurture. Many primitive religions identify the sun with God, for good reason.
Beyond this visible world, which later philosophers (esp. Immanuel Kant) would call thephenomenal world, lies an intelligible world (that Kant will call noumenal. The intelligible world is (metaphorically) illuminated by "the Good" (τον ἀγαθὸν), just as the visible world is illuminated by the sun.
The division of Plato's Line between Visible and Intelligible is then a divide between the Material and the Ideal, the foundation of most Dualisms. Plato may have coined the word "idea" (ἰδέα), using it somewhat interchangeably with the Greek word for shape or form (εἶδος ). The word idea derives from the Greek for "to have seen."
Plato's Line is also a division between Body and Mind. The upper half of the divided line is usually called Intelligible as opposed to Visible, meaning that it is "seen" by the mind (510E), by the Greek Nous (νοῦς), rather than by the eye.