What the ears have not encountered is called the strange; when judged by the ordinary, the strange is lightly dismissed.
What the eyes and ears can perceive is called the constant.
Sound is merely what the ears hear, yet what gives rise to sound was not first heard by the ears.
Form is merely what the eyes see, yet what gives rise to form was not first seen by the eyes.
Recorded from Donglai Boyi. Corrected by Mr. Shiyi. Inscribed by Xiang Tai.