大乘起信論裂網疏 3.33

3.33

Previously, it was explained that the ālayavijñāna has two kinds of aspects, namely enlightenment and non-enlightenment; now, identity and difference are distinguished on this basis. When tathatā accords with conditions yet is immutable, in exhausting its entire essence to become the ālayavijñāna, it exhausts its entire essence to become enlightenment and non-enlightenment. When enlightenment and non-enlightenment accord with conditions yet are immutable, in exhausting their entire essence to rely on the ālayavijñāna, they exhaust their entire essence to be tathatā. Now, in terms of according with conditions yet being immutable, arising and ceasing is tathatā, hence it is called the mark of identity; in terms of being immutable yet according with conditions, tathatā is arising and ceasing, hence it is called the mark of difference. Therefore, the text above says: "The two aspects mutually do not part from one another."