How do dreams appear? How many consciousnesses are there in a dream?

Dreams arise from the manas' grasping and clinging to things one has experienced and things one has never experienced; the tathāgatagarbha, in accordance with that grasping, manifests the dream. The manas' grasping and clinging nature belongs to the manas' imputed nature (parikalpita-svabhāva). All the mental activities of the manas are known by the tathāgatagarbha; having known them, it follows the manas' mental intentions and the sentient being's karmic force to manifest the dream, allowing the sentient being to continue grasping and clinging within the dream. If the manas does not grasp and cling, the tathāgatagarbha will not actively manifest a dream.

Therefore, for some people, once their cultivation becomes effective, their dreams gradually change from turbid to pure, and from many dreams to few. This is because their cultivation has penetrated deep into the manas; after the manas has been perfumed, ignorance is lightened and the clinging nature is reduced. As for arhats, because their manas has completely severed the afflictions of self-grasping and eliminated craving for worldly phenomena, they very rarely have dreams.

Within a dream, three consciousnesses—the sixth, seventh, and eighth consciousnesses—are actively operating; the first five consciousnesses are absent. Therefore the images in dreams are hazy, unlike when awake. When awake, the five sense-object realms are all clear and distinct, whereas in dreams the five sense-object realms are not clear and distinct. Although after waking one feels that the eyes also saw material sense-objects, one cannot see the colors of people and things. Although one can sense colors, sense spaciousness, and sense light and darkness, that is only the mind consciousness's sensing, not the eye consciousness truly seeing these scenes. The realms seen in dreams differ greatly from those seen when awake.

For example, seeing people from past lives, or seeing people from other worlds—these cannot be what the eye consciousness sees. The eye consciousness absolutely cannot see people from past lives or from other worlds; otherwise all sentient beings would possess the divine eye. Without supernatural powers and the divine eye, the eye consciousness cannot possibly see people and things of past lives, cannot possibly see people and things of future lives, and cannot possibly see people and things of other worlds. If the eye consciousness could see them, then the eye faculty would be able to face those material sense-objects; in fact, the eye faculty cannot face those material sense-objects and cannot reach them. Otherwise, the eye faculty could go to past lives and other worlds, and the body faculty could also go to other worlds; in fact, the body is still sleeping in bed and has gone nowhere.

A dream is a solitary mental-object realm (an Image-Only Object), a realm of mental sense-objects manifested by the tathāgatagarbha directly transmitting seeds; only the manas and the sixth consciousness can reach it, and the one that can truly discern it clearly is only the sixth consciousness. The eighth consciousness transmits karmic seeds and manifests the realm of mental sense-objects in the dream because the manas has the nature of grasping and clinging. The manas grasps, the eighth consciousness complies, and the dream is thus manifested. "What is thought of by day is dreamed of by night" illustrates this principle: it is precisely because of what the manas' mental-faculty deliberation thinks and considers that the eighth consciousness manifests the dream.