The Brain Determines the Strength of Conscious Functions.

What is the difference between the solitary consciousness (mano-vijñāna-eka-citta) in dreams and the solitary consciousness outside of dreams? During sleep, the circulation of qi and blood weakens, and the circulation of qi and blood in the brain also weakens. The six consciousnesses arise and operate by relying on the brain as the supreme faculty (indriya). After the solitary consciousness arises in a dream, due to the condition of the supreme faculty, the functions of the mind consciousness are relatively weak; the mind consciousness's discernment within the dream is not clear or detailed enough, and what is remembered is not firm. If the manas considers the dream to be very important, and it is greatly stimulated by it, the impression will be deep, and it will cause the solitary consciousness to deepen the impression. After waking up, the mind consciousness can remember it vividly and recall the dream very clearly.

Due to external forces, the brain may be injured, causing unconsciousness, and the six consciousnesses disappear. After waking up, some people will suffer amnesia. This is because the brain is damaged, obstructing the functioning of the mind consciousness; the mind consciousness's function of integrating information becomes disordered or weakened, resulting in the inability to recall people and events from a certain period of time. Once the brain receives a strong stimulation, the mind consciousness may possibly recover its memory and recall people and events from the past. The memories of childhood and early years are not firm because the brain is not fully developed, resulting in weak functions of the mind consciousness and unreliable memory. The mind consciousness of the elderly is generally weaker in function than in their youth; their discernment is not detailed and their thinking is coarse—this is what is called senility.

When the circulation of qi and blood is not smooth, it will damage the brain, and a person will become foolish and demented. Therefore, the six consciousnesses are of the nature of dependence on others (paratantra), are dharmas produced by causes and conditions, are extremely false and illusory, and cannot be relied upon; the six consciousnesses are not the self, nor are they belonging to the self. In the neutrino-body (antarā-bhava), the functions of the mind consciousness are even weaker, because the antarā-bhava arises temporarily, its four great elements are coarse and inferior, far inferior to the human body, and severely obstruct the functions of the mind consciousness. Therefore, in the antarā-bhava, the mental activities of the manas are dominant; the mind consciousness cannot effectively regulate the manas, and the inherent nature of the manas determines the destination of the next life. Therefore, realization of the fruits by the mind consciousness alone is a fruit made of paper; only when the manas realizes the fruits at the same time will the realization be firm and non-retrogressive, and be carried into future lives.