金剛經纂要刊定記 3.175

3.175

右膝下。右則為順，膝能迴屈，表順理心也。著地即示卑之相也。膝表智，地表理，合掌即表冥心，掌合不執外物，心冥覺不異緣，欲問實相法門故，須用心如此。

On "the right knee, etc.": the right signifies compliance, and the knee is able to bend, symbolizing a mind compliant with principle. Touching the ground manifests the mark of lowliness. The knee symbolizes wisdom, and the ground symbolizes principle. Joining the palms symbolizes merging the mind: when the palms are joined, they do not grasp external objects; when the mind is merged, awakening does not diverge from conditions. Wishing to inquire about the Dharma gate of ultimate reality, he thus had to apply his mind like this.