On the Supreme Faculty

All sentient beings in the human realm possess the supreme faculty (indriya), and sentient beings in the animal realm also possess the supreme faculty. The physical bodies of animals, like those of humans, are flesh bodies composed of the four great real seeds; they have brains and supreme faculties. When the supreme faculty develops pathological changes, animals can also become schizophrenic or insane. Due to karmic obstructions, the supreme faculties of animals are inferior to those of humans; their perception of people and things involves great illusions, and they do not see the Dharma as it truly is. However, each kind of animal has special strengths belonging to its own species: for example, some animals have keen vision and can see at night, some have keen hearing, some have keen smell, some have keen taste, and some have keen touch. But generally speaking, animals have very poor deliberative capacity of the mind consciousness, and even less capacity for logical analysis; they mostly rely on the intuitive power of the manas, and thus appear relatively simple. Apart from the killing karma committed for the sake of filling their bellies and surviving, they almost never use their minds to create other unwholesome karma; they are sentient beings who purely undergo retribution.

Sentient beings in the four formless heavens of the formless realm, because their living environment is formless, have no material form or the five sense objects, and no physical body; therefore they have no supreme faculty, no inner five sense objects, and no inner mental sense objects, and no five sense consciousnesses; yet they do have the mind consciousness, the manas, and the eighth consciousness. Their eighth consciousness and manas exist forever without perishing, and their mind consciousness also exists forever without perishing. What their mind consciousness discerns is the subjectively imagined realm within meditative concentration; there is no external mental sense object, only the subjectively imagined realm. If the mind consciousness were to cease, only the eighth consciousness and the manas would remain, which would belong to the state of the cessation absorption. Therefore, the mind consciousness of the beings in the formless realm also exists forever without perishing; there is no distinction between day and night, they do not need sleep or rest, and they remain forever in meditative concentration, facing the subjectively imagined realm.