Why Has the Manas Existed Since Beginningless Eons?

Since beginningless kalpas, there have been two dharmas that did not arise from causes and conditions. One is the eighth consciousness, the tathāgatagarbha, which exists inherently and originally, without needing any dharma to give birth to it. The other is the manas, the seventh consciousness, which has also existed together with the eighth consciousness from the very beginning; it is not a dharma born later, nor was it produced by the eighth consciousness through any conditions. However, the manas is still a conditioned, arising-and-ceasing dharma, an unreal dharma; it requires the eighth consciousness to continuously output consciousness seeds in order to sustain its existence, and it can only exist through the eighth consciousness's continuous upholding of it.

Why is it that the manas, which has existed since before beginningless kalpas and was not born of causes and conditions, still belongs to the category of dharmas subject to arising, ceasing, and change? Because the manas has possessed ignorance (avidyā) inherently since before beginningless kalpas—especially the ignorance of a single thought, the afflictions of greed, anger, and delusion—and it does not know that it itself is illusory. Therefore, the view of self (satkāya-dṛṣṭi) and self-grasping cannot extinguish it, and it coexists alongside the eighth consciousness without disappearing. Once the manas has completely severed the ignorance of a single thought, self-grasping will be completely severed, and it will inevitably vanish, leaving only the eighth consciousness existing alone—formless and without appearance, without clamor or disturbance, in the tranquility of nirvāṇa.