大乘起信論裂網疏 2.21

2.21

Question: The advancements of true cultivation are indeed not called deluded thoughts; but when emerging from contemplation, subtle deluded thoughts of ignorance still become active—how can they be called "entirely exhausted"? Answer: If upon emerging from contemplation a subtle deluded thought occasionally arises, that is not called accordant. As the saying goes, "Only a sage who neglects mindfulness becomes foolish." If at [the stage of] verbal understanding one can know that deluded thoughts lack self-nature, that is also called accordant, as the saying goes, "Only the foolish who master mindfulness become sages." In brief, the principle-identity is pure discordance, while the ultimate is pure accordance. From verbal understanding on up to virtual enlightenment and below, discordance and accordance are entirely intermingled. It is like the waxing moon from the first night to the fourteenth night: although the light gradually increases, the dark aspects are not yet exhausted. But having partially realized, one has attained the untainted and never regresses. It is like the crescent moon when first appearing, whose light shines upon the great earth; it may also be called "deluded thoughts entirely exhausted". The first part, correctly explaining the mark of tathatā of this mind, is concluded.