金剛經纂要刊定記 1.30

1.30

復次，兩句更互釋成。以上句釋下句，成色空義。以下句釋上句，成心淨義。色若不空心則不淨，心若不淨色即不空。由心淨故色空，由色空故心淨。以色心二法不相離故，當知由心淨故方能現色。如鏡淨故方能現像，染則不能。又由色空故不能染心，如像空故不能污鏡，實則污也。上句下句法喻對明、反覆相成，故云互釋。

Furthermore, the two clauses mutually explain and complete each other: using the upper clause to explain the lower clause completes the meaning of form being empty; using the lower clause to explain the upper clause completes the meaning of the mind being pure. If form were not empty, the mind would not be pure; if the mind were not pure, form would not be empty. Because the mind is pure, form is empty; because form is empty, the mind is pure. Because the two dharmas of form and mind are inseparable, one should know that only because the mind is pure can it manifest form. Just as only because a mirror is pure can it manifest images, whereas if defiled it cannot. Furthermore, because form is empty, it cannot stain the mind; just as because an image is empty, it cannot defile the mirror, whereas if real, it would defile it. The upper and lower clauses, Dharma and metaphor, are clarified in contrast to each other, recurrently complementing one another; hence it is called mutual explanation.