金剛經纂要刊定記 2.75

2.75

且本舉能堅能利一金剛，以喻觀照、實相二種般若。若單取觀照則闕堅義，若單取實相則闕利義。又皆言即者。釋成不二之相。以照而常寂故理非智外，寂而常照故智非理外。既離理無智、離智無理，故如金剛即堅即利。

Furthermore, one diamond, which can be hard and can be sharp, was originally adduced to serve as a metaphor for the two kinds of prajñā: contemplative and ultimate-reality. If one took contemplative [prajñā] alone, the meaning of "hard" would be missing; if one took ultimate-reality [prajñā] alone, the meaning of "sharp" would be missing. Moreover, both using "precisely" explains and establishes the characteristic of non-duality. Because while illuminating it is constantly still, principle is not outside wisdom; because while still it is constantly illuminating, wisdom is not outside principle. Since apart from principle there is no wisdom, and apart from wisdom there is no principle, it is like a diamond being both hard and sharp.