大方廣圓覺修多羅了義經略疏 2.223

2.223

即《論》四位中前三，覺前不覺後也。謂障習漸盡，如一分塵盡、一分鏡明。

This corresponds to the first three of the four stages in the *Treatise*, awakening to the earlier but not yet to the later. That is to say, as the habits of obstruction are gradually exhausted, it is like a portion of dust being exhausted and a portion of the mirror becoming bright.