How to Understand the 'Constant' in the Constant Mental Deliberation of Manas

Question: If the manas (mind faculty) is also a phenomenon subject to arising and cessation, how should the "constancy" in its "constant mental deliberation" be understood? 

Answer: "Constancy" signifies an extremely long and enduring duration. The constancy of the manas can persist even after attaining Buddhahood, without being extinguished. However, not extinguishing it does not mean the manas cannot be extinguished. Arhats and Pratyekabuddhas can completely extinguish the manas to enter Parinirvāṇa (final nirvana without residue). Bodhisattvas above the seventh stage and all Buddhas can extinguish the manas but deliberately choose not to do so. The manas is produced by the ālaya-vijñāna (storehouse consciousness) transmitting seeds of consciousness; it depends on the ālaya-vijñāna for its arising and functioning. It is not the originally unborn and unceasing fundamental reality. Once the manas no longer clings to worldly phenomena of the three realms, the ālaya-vijñāna ceases to transmit the seeds of consciousness for the manas, and the manas is then extinguished. Therefore, the "constancy" in the manas's "constant mental deliberation" is only relative to the six consciousnesses and cannot compare to the constancy of the ālaya-vijñāna. The constancy of the ālaya-vijñāna is absolute and incomparable, while the constancy of the manas is relative.