大乘起信論廣釋卷第三．四．五 5.69

5.69

Treatise: "All signs... thought after thought do not perish."
Commentary: This is separating from the inverted mind. "All signs," etc., means eliminating the signs of the internal mind. All signs arise based on thoughts; once thoughts are eliminated, all signs perish along with them. Hence it says, "all signs are completely eliminated along with thoughts."
Another interpretation says: this indicates that [tathatā] is profound and cannot be thought or conceptualized; why make a distinction and speak of "along with"? Therefore the new translation of the treatise says: "all conceptual signs and thoughts are all followed," so there is no distinction. This means that although one previously abandoned grasping, if the signs of inverted objects remain in the internal mind, that too is deluded inversion. Therefore, even if all conceptual signs and thoughts arise in the internal mind, they are all dispelled.
"Also dispelling the sign of elimination": this dispels the deluded sign of the active eliminator. The preceding text only meant that not giving rise to the signs of the internal mind's discrimination is called "eliminating signs"; it did not mean maintaining a sign of an active eliminator. If the sign of elimination remains, that too is not separation from signs; therefore, one also dispels the sign of elimination.
"Because all..." below explains the reason for also dispelling the active eliminator. Because all dharmas originally have no characterised object (lakṣya), since the characterised object does not exist, the active characteriser (lakṣaṇa) does not exist either, having no substance of arising and ceasing thought after thought. Since the sign to be eliminated is already impossible to eliminate, how could one further eliminate while maintaining a sign of an active eliminator?