Why in Dreams Do We Not Know We Are Dreaming?

In a dream, who is the one that knows it is a dream? When awake, who is the one that knows sense objects? Both within and outside the dream, both the sixth and seventh consciousnesses have knowing, with the knowing of the sixth and seventh consciousnesses as the primary factor; the five sense consciousnesses can only know the five sense objects in reality, and cannot know the objects within a dream.

The knowing nature of the mind consciousness is greatly related to the physical body. When the physical body has obstructions, the knowing of the mind consciousness becomes weak or ceases. For a person who has attained the four dhyānas and eight samādhis, the physical body has no obstructions, and the knowing of the mind consciousness is clear and vast; whether asleep or not, one can know with great clarity, and no matter how many bottles of wine one drinks, one will not become drunk, because alcohol can no longer paralyze the central nervous system of the brain, and thus the mind consciousness is unaffected.

The knowing of the mind consciousness is also greatly related to the knowing of the seventh consciousness (manas). Generally speaking, the seventh consciousness knows all dharmas; the question is only whether it knows them as they truly are. As for the portion that the seventh consciousness can know as it truly is, how it can influence the mind consciousness so that the mind consciousness also knows, and promptly processes what is known—that involves the capacity for communication between the two consciousnesses. What is called the capacity for communication is wisdom; how what the mind consciousness knows can effectively influence and permeate the seventh consciousness also involves the capacity for communication, that is, how good the wisdom is.

Wisdom is also closely related to meditative concentration (samādhi). Meditative concentration can make the mind quiet, peaceful, and steady, enhance the capacity for thinking, and make the power of wisdom great; thus the mutual influence between the two consciousnesses becomes great. Meditative concentration can also make the physical body unobstructed; with the physical body unobstructed, the mind consciousness has no hindrance, its knowing is keen and unimpeded, and it can effectively influence the seventh consciousness. Conversely, the seventh consciousness can also effectively influence the mind consciousness; the two communicate and exchange with each other, and knowing all dharmas becomes smooth with little obstruction.

Knowing the dream as a dream whether awake or dreaming is a wisdom realm cultivated through practice; knowing that it is a dream and not being trapped by the dream-state is wisdom. This cultivation mainly refers to meditative concentration; meditative concentration is an indispensable link in practice—only with meditative concentration can wisdom be developed, making the knowing of the sixth and seventh consciousnesses more truthful and more in accord with principle, knowing more truly, more subtly, and more vastly. And only by removing the hindrance of sleep can deep meditative concentration arise. For a person with deeper meditative concentration, thinking is clear when awake, and even in dreams there is no delusion—just as when awake—knowing the states without obstruction.

The knowing of ordinary people has obstructions—that is what is colloquially called lacking supernatural powers—whereas the knowing of a person with supernatural powers is unobstructed, having the power of knowing others' minds, the divine eye, and so on. This is the karmic retribution of the merit of concentration and wisdom; knowing the dream as a dream is the retribution attained by a person whose meditative concentration is very good and whose mind has become purified. Ji Gong the monk had the four dhyānas and eight samādhis and had supernatural powers; no matter how much wine he drank, his nervous system was not affected or anesthetized, and his mind consciousness was always awake, able to observe and know all states as they truly are. For ordinary people, after falling asleep the mind consciousness ceases, and that portion of the manas's function of knowing states by relying on the mind consciousness no longer operates; therefore, when dreaming, the manas's power of discernment is weak and it does not know it is a dream, and the solitary consciousness (mano-vijñāna-eka-citta) within the dream also has very weak discernment and likewise does not know it is a dream. But a person with cultivation, whose power of meditative concentration is strong, whose physical body is unobstructed, and whose sixth and seventh consciousnesses are clear, has strong discernment; while dreaming, he knows it is a dream and is not deluded. 

Master Kuiji had the four dhyānas and eight samādhis and had supernatural powers; when sleeping at night he was extremely clear—clearer than ordinary people are when awake. His sixth and seventh consciousnesses were so keen that after he fell asleep, when a leg of a louse fell off and it cried out in pain, Master Kuiji could hear it—this is the merit of the power of meditative concentration and supernatural power. Being able to hear the cry of a louse while asleep—does this not show that he was not truly asleep? For ordinary people, sleep is a kind of covering that can obscure their minds so that they neither see nor hear, like dead people. But for a person who has eliminated the covering of sleep, very little sleep is enough to nourish the physical body; his meditative concentration will reach the first dhyāna or above, his mind is clear, his obstructions are slight, or there are no obstructions at all; during sleep his mind consciousness is not necessarily completely cut off, yet his sleep is still sufficient—this differs from ordinary people.

Especially for a person with supernatural powers, his sleep is like being awake, even clearer than ordinary people are when awake. In ancient times, people with martial arts skills also slept lightly and had high alertness. This alertness can be said to belong to the mind consciousness, but the manas indeed also has alertness; its alerting of the mind consciousness is still a very strong function, so without the manas, the functions of the mind consciousness cannot be fully explained. Sleep and torpor are of the same category, both belonging to the hindrances and coverings, which can obscure the light of the conscious mind. Only after the hindrance and covering of sleep is eliminated will the concentration of the first dhyāna appear. The deeper the torpor when sleeping, the poorer the meditative concentration, or there is no meditative concentration and the coverings are heavy; the more deluded one is in dreams, the less meditative concentration one has; the more easily one becomes drunk, the greater the obstruction of the physical body and the less meditative concentration one has. Those with deep meditative concentration can regulate the physical body well, unaffected by environmental factors, without obstructing the functioning of the six consciousnesses. Therefore, the power of concentration is extremely important; even if one does not study Buddhism or cultivate, if meditative concentration is well cultivated, the benefits are very great.