首楞嚴義疏注經 2.119

2.119

「如人以手指月示人，彼人因指當應看月。若復觀指以為月體，此人豈唯亡失月輪，亦亡其指。何以故？以所標指為明月故。」

"'Just as a person uses a finger to point at the moon to show someone, that person should look at the moon by means of the finger. If he instead looks at the finger and takes it to be the substance of the moon, this person not only loses the disc of the moon, but also loses his finger. Why? Because he takes the pointing finger to be the bright moon.'"