The Differences in the Supreme Faculties of Sentient Beings in Each Realm

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 constituted by the four great real seeds; they have brains and have the supreme faculty. When the supreme faculty develops pathological changes, animals can also become schizophrenic or insane. Due to karmic obstructions, the supreme faculty of animals is inferior to that of humans; their perception of people and things involves great illusion, and they do not see dharmas as they truly are. However, various animals each have special strengths belonging to their own kind: 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, so they appear rather simple. Apart from the killing karma committed for the sake of filling their bellies and surviving, they almost never use their minds to commit other evil karma; they are sentient beings that 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 or inner mental sense objects, and no five 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 of perception and feeling (nirodha-samāpatti). Therefore, the mind consciousness of beings in the formless heavens 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.