The External Mind and the Internal Mind in the Great Discourse on the Establishing of Mindfulness

In the Mahasatipatthana Sutta, the Buddha, when discussing the Five Hindrances, spoke of internal sensual desire and external sensual desire, internal ill will and external ill will, internal sloth and torpor and external sloth and torpor, internal restlessness and remorse and external restlessness and remorse, internal doubt and external doubt. What do internal and external respectively refer to?

If the mind is divided into internal and external, the external mind refers to the mental consciousness that sentient beings can generally perceive and observe, while the internal mind refers to the mental faculty of manas that sentient beings find difficult to perceive and observe. These two types of consciousness are distinct: one is manifest, the other hidden; one is apparent, the other obscure; one is superficial, the other deep; one is easily altered, the other is firmly entrenched and difficult to change. Spiritual practice first addresses the superficial level of consciousness before progressing to the deeper level of manas. It begins by initially transforming consciousness and ultimately brings about the complete transformation of manas. Therefore, all afflictions and ignorance are initially and most evidently present at the level of consciousness, but ultimately and most profoundly rooted at the level of manas.

From this sutra, we can see that although the Buddha did not explicitly teach the dharma of manas when expounding the Hinayana teachings, he nonetheless implicitly addressed manas. He implied that all afflictions and ignorance pertain to manas; that the cessation of afflictions is the cessation of the afflictions of manas; that liberation is the liberation of manas; that all dharmas are ultimately grounded in manas; and that by resolving the problem of manas, one resolves all dharmas, ultimately attaining complete Nirvana and liberation.