Why Can a Defiled Manas Only Give Rise to Defiled First Six Consciousnesses?

Because the first six consciousnesses arise based on the volition (cetanā) of the manas, they manifest whatever the manas requires; whatever the manas needs, the six consciousnesses arise to perform accordingly. Thus, if the manas is defiled, the six consciousnesses will consequently engage in defiled karmic actions; if the manas is pure, the six consciousnesses will consequently engage in pure karmic actions. According to the root cause of sentient beings' cyclic existence in birth and death, as elucidated by the Twelve Links of Dependent Origination, it is because the manas possesses ignorance. Based on ignorance as the condition, the karmic formations of ignorance in the manas arise. Based on the karmic formations of ignorance in the manas as the condition, the bodily, verbal, and mental actions of ignorance in the six consciousnesses arise. All bodily, verbal, and mental actions are deposited into the ālaya-vijñāna, becoming seeds.

The karmic formations of the manas refer to its volitional choices. After the manas makes a choice, the six consciousnesses arise to assist the manas in its actions. Therefore, if the manas is defiled and possesses ignorance, the six consciousnesses, as its assistants, must aid the manas in performing defiled karmic actions. If the manas is defiled but does not choose defiled actions, the mental consciousness may rely on its own purity to influence the manas, and the manas may also endorse the pure actions of the mental consciousness, thereby giving rise to pure karmic actions. Thus, spiritual practice entails cultivating wholesome dharmas and using these wholesome dharmas to influence the manas, thereby eradicating the ignorance within the manas and transforming it. When the mind becomes pure, one will experience pure karmic fruits in the future.