大方廣佛華嚴經疏 28.47

28.47

Forty: In giving the nails attached to the flesh, the phrase "marks of red copper" refers to minor characteristics. The five being peerless: the phenomenal nails are not defiled by dust and grime; the wisdom nails are not defiled by the marks of sensory objects. The phrase "well-born" is because they are born of good karma. Some say that in the dialect of the Western Regions, "well-born" means well-proportioned and handsome. The rest is intelligible. Why, in seeking the Dharma, does one specifically speak of giving the nails? First, it is because there is an actual event in the cited precedents. Entering fire to seek the Dharma below is also understood according to this. Second, it has a symbolic meaning: because nails can scratch and seize, it accords with the meaning of seeking. Entering fire to seek below symbolizes that it is difficult to grasp. Therefore, the Dazhidulun says: "Prajñāpāramitā is like a great mass of fire; it cannot be grasped from the four sides, and being ungraspable, it is also not grasped."