Now if human beings, considered in the terms of the "allegory," were suddenly, while still within the cave, to glance back at the fire whose radiance [121 {GA 9: 215}] produces the shadows of the things being carried back and forth, they would immediately experience this unaccustomed turning around of their gaze as a disruption of customary behavior and of current opinion. In fact, the mere suggestion of such a strange stance, to be adopted while still within the cave, is rejected, for there in the cave one is in clear and complete possession of the real. The people in the cave are so passionately attached to their "view" that they are incapable of even suspecting the possibility that what they take for the real might have the consistency of mere shadows. But how could they know about shadows when they do not even want to be aware of the fire in the cave and its light, even though this fire is merely something "man-made" and hence should be familiar to human beings? In contrast, the sunlight outside the cave is in no way a product of human making. In its brightness things that have grown and are present show themselves immediately without needing adumbrations to represent them. In the "allegory" the things that show themselves are the "image" for the "ideas." But the sun in the "allegory" is the "image" for that which makes all ideas visible. It is the "image" for the idea of all ideas. This latter, according to Plato, is called ἡ τοῦ ἀγαθοῦ ἰδέα, which one translates with the "literal" but quite misleading phrase "the idea of the good."

The allegorical correspondences that we have just now enumerated — between the shadows and reality as experienced every day, between the radiance of the cave fire and the light in which the habitual and closest "reality" stands, between the things outside the cave and the ideas, between the sun and the highest idea — these correspondences do not exhaust the content of the "allegory." In fact, the proper dimension of it has not even come into our grasp yet. The "allegory" recounts a series of movements rather than just reporting on the dwelling places and conditions of people inside and outside the cave. In fact, the movements that it recounts are movements of passage out of the cave into the daylight and then back out of the daylight into the cave.

[122 {GA 9: 216}] What happens in these movements of passage? What makes these events possible? From what do they derive their necessity? What issue is at stake in these passages?

The movements of passing out of the cave into the daylight and then back from there into the cave require in each case that the eyes accustom themselves to the change from darkness to brightness and from brightness back to darkness. Each time, in so doing, the eyes experience confusion, indeed for opposite reasons in each case: διτταὶ καὶ ἀπὸ διττῶν γίγνονται


Martin Heidegger (GA 9) Pathmarks