大方廣圓覺修多羅了義經略疏 2.262

2.262

若理法界，則法界體中絕諸勞慮，塵境不生，名之為淨。若事法界，則分別念慮之心、差別塵境之法，十八界等當體不生，名之為淨。何者？法界淨穢皆由自心，心穢則穢，心淨則淨。

If [viewed from] the dharmadhātu of principle, then within the substance of the dharmadhātu all labor and distress are terminated and defiling objects do not arise; this is called "purity." If [viewed from] the dharmadhātu of phenomena, then the mind of discriminating thoughts and the phenomena of differentiated defiling objects, such as the eighteen dhātus, inherently do not arise in their very substance; this is called "purity." Why so? The purity or defilement of the dharmadhātu entirely depends on one's own mind: if the mind is defiled, it is defiled; if the mind is pure, it is pure.