The Four Stages of the Occurrence of Truth

first necessary to distinguish the way in which e.g. a sheet of glass (even coloured glass) is transparent, from the transparency of light. Comparing the two kinds of letting-through will allow us to more accurately determine the essence of light as what lets-through.

We call glass transparent, even when it is coloured (e.g. a window pane), and likewise water. The question is whether brightness (light) is transparent in the same sense. Evidently not, and not only because brightness is not graspable in the way a sheet of glass or a body of water are, but because the transparency of glass and water, and of everything similar, already presupposes brightness. These kinds of things are only transparent in light; only in light can anything be seen through them. Sight in general, and thus also the sight that penetrates, is first made possible by light. Light (brightness) too is transparent, but in a stricter sense: as the genuinely originally transparent. We see two things: light first lets the object through to be viewed as something visible, and also lets-through the view to the visible object. Light is what lets-through. Brightness is visibility, the opening and spreading out of the open. Thus we have defined the genuine essence of brightness: it allows things to show themselves for viewing, it offers a look [Anblick] for seeing [Sehen] in the narrower meaning of perceiving through the sense of sight.

Correspondingly with the dark. This is only a limit case of brightness and thus still has the character of a kind of brightness: a brightness that no longer lets anything through, that takes away visibility from things, that fails to make visible. It is what does not let-through, but in a quite specific sense, different, for example, to the way a wooden wall is untransparent, does not let-through, A wooden or brick wall cannot fail in making visible, for in no sense can it secure visibility; it is untransparent in quite a different way to that of darkness. To indicate just one aspect of this difference: for a wall to be spoken of as untransparent, as not letting-through (for someone), light must already be assumed as present, while on the other hand, the not letting-through of the dark consists precisely in the absence of light (brightness) and in this alone. The dark is untransparent because it is itself a kind of letting-through. The wall is untransparent because it is not any kind of letting-through (for sight). Only that can fail which also has the possibility of securing. The dark fails to make visible because it can also secure sight: in the dark we see the stars.

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