Consider the image utilized to reveal the Dharma-eye’s capacity to see nondually in Dogen’s expression, “When one side is illumined, the other side is darkened.” Seeing total existence-time as a particular form is seeing what “is illumined”; seeing a particular form as a specific instance of total existence-time is seeing (accounting for) what “is darkened.” To see (illumine) “this side” of an apple is to see “that side” of the apple darkened; seeing “this side” depends on, and therefore confirms, the presence of “that side” – thus, seeing “this side” of the apple is seeing the whole apple as it is; half-illumined half-darkened. Likewise, in seeing any/every particular form, the Dharma-eye confirms the presence of the totality of the self. One of the clearest mythopoeic expressions of this is presented in the Surangama Sutra, from which it was adapted by Zen and elaborated in a number of koan collections. The particular image in question appears, for example, as the main koan of case 94 of the Hekiganroku:
The Surangama Sutra says: When I don't see, why don’t you see my not-seeing? If you see my not-seeing, it could not be the nature of not-seeing. Since you don’t see my not-seeing, it is naturally not a thing (i.e. dharma). How could it not be you?
Hekiganroku (Blue Cliff Record), Case 94 (main case)
If we discern the wisdom transmitted here, we see that the extent of our enlightenment is precisely matched by the extent of our delusion. No matter how many times or how fast we spin the apple, seeing it will always depend on illumining one side and darkening the other. Similarly, no matter how expansive enlightenment is, it will always correspond exactly with delusion. Seeing one’s true nature confirms this truth; great enlightenment is our inherent ability to intelligibly discern whatever we illumine, great delusion is the inherent dependence of illumination on darkening – to illumine anything is to darken everything else.
Thus, language becomes ascesis, instead of gnosis or logos—‘seeing things as they are’ now means ‘making things as they are.’ In this light the indexical analogy of ‘the finger pointing to the moon’ is highly misleading, if not altogether wrong, because it draws on a salvifically inefficacious conception of language.
Hee-Jin Kim, Dogen on Meditation and Thinking, p.64