請觀音經疏闡義鈔 1.59

1.59

「八萬四千塵勞」者，真諦三藏準《十使經》，以貪等十為根本，謂貪乃至戒取一一有九，隨眠一，即成十。十即成百，前後等分各一百，成三百。置本一百，就前後二百中又各以十使為方便，二百即成二千一百。約五類眾生，謂多貪、多瞋、多癡、著我、思覺，五品各二千一百，即成一萬五百。配已起未起，成二萬一千。又配貪、瞋、癡、等分，此四各有二萬一千，成八萬四千也。今云「四分開出」者，惑數雖多，四分收盡。

"Eighty-four thousand defilements of dust": Tripiṭaka Master Paramārtha, basing himself on the Sūtra on the Ten Proclivities, takes the ten, such as greed, as fundamental: meaning that greed up to clinging to rules each has nine, plus one dormant disposition, thus making ten. Ten then makes one hundred; the prior, subsequent, and equal portions are each one hundred, making three hundred. Setting aside the original one hundred, among the two hundred prior and subsequent ones, taking each of the ten proclivities as an expedient means, the two hundred then becomes two thousand one hundred. In terms of the five types of sentient beings—namely, those with excessive greed, excessive anger, excessive delusion, attachment to self, and discursive thought—the five classes each with two thousand one hundred then makes ten thousand five hundred. Matching arisen and not yet arisen makes twenty-one thousand. Further matching greed, anger, delusion, and equal portions, these four each have twenty-one thousand, making eighty-four thousand. Now, saying "developed through the four divisions" means that although the number of afflictions is great, they are fully subsumed under the four divisions.