大乘起信論裂網疏 4.110

4.110

This very momentary mind right before us has tathatā as its nature. Sentient beings falsely see arising and ceasing within tathatā, just as a lost person takes east to be west; thus, outside of tathatā there is no arising and ceasing. Although the lost person takes east to be west, east still remains east; thus, what the lost person calls west was originally the east of the person who understands, which can be an analogy for there being no tathatā outside of arising and ceasing. Taking the mind to be moving matches the earlier taking east to be west; this is tathatā becoming arising and ceasing. The mind being actually unmoving matches the earlier east still remaining east; this is there being no tathatā apart from arising and ceasing. Therefore, if one can know that the moving mind is itself neither arising nor ceasing—analogous to being able to know that what was called west is originally east—one immediately enters the aspect of tathatā. The one mind is divided into the two aspects of delusion and awakening, but the two aspects are ultimately only this one mind; the only essential thing is to overturn that deluded perception with knowing. Delusion is avidya. Taking [something to be so] is deluded thinking. Knowing is initial awakening. It should fundamentally be understood in this way, with no other separate knowing; therefore it is said that initial awakening is original awakening. The first part, showing the real meaning, is concluded.