瑜伽論記 19.161

19.161

前中，云䨱慧勝慧者，猶如䨱鉢不受物，鈍慧亦爾不受法故。言䨱慧猶膝上著草子等時，坐時著起時即落散，鈍慧亦爾，坐時聽法起即忘失，故言膝慧。

In the former part, where it speaks of 'inverted wisdom' and 'superior wisdom': just as an overturned bowl does not receive things, dull wisdom is also like this because it does not receive the Dharma. As for saying 'inverted wisdom' is like when grass seeds and the like are placed on the knees, when sitting they stay, but when standing up they immediately fall and scatter; dull wisdom is also like this—when sitting listening to the Dharma [it is retained], but upon rising it is immediately forgotten and lost, hence it is called 'knee wisdom'.