How Do Dreams Arise? How Many Consciousnesses Exist Within Dreams?

Dreams arise from the clinging and grasping of the mental faculty (manas) towards experiences both encountered and unencountered. The Tathagatagarbha, complying with this grasping, manifests the dream state. The grasping and clinging nature of the mental faculty belongs to its characteristic of parikalpita-svabhava (imagined self-nature). All mental activities of the mental faculty are known by the Tathagatagarbha. Having known them, it then manifests dreams in accordance with the mental faculty's thoughts and the karmic forces of sentient beings, allowing them to continue clinging and grasping within the dream. If the mental faculty does not grasp and cling, the Tathagatagarbha will not actively manifest dreams.

Therefore, when some practitioners attain effective cultivation, their dreams gradually transform from turbid to pure, and from frequent to infrequent. This is because their practice has penetrated deeply into the mental faculty. After being influenced by cultivation, the mental faculty experiences diminished ignorance and reduced clinging. The mental faculties of Arhats, having completely severed self-attachment afflictions and eliminated greed for worldly phenomena, rarely manifest dreams.

Within the dream state, the three consciousnesses—the sixth consciousness (mano-vijnana), the seventh consciousness (manas), and the eighth consciousness (alaya-vijnana)—manifest and operate. The five sense consciousnesses are absent. Consequently, dream images are hazy and differ from the waking state. In wakefulness, the objects of the five sense fields are clear and distinct, whereas in dreams, the objects of the five sense fields are not clear or distinct. Although upon waking, one may feel as if the eye consciousness saw form objects, it cannot perceive the colors of people or things. Although one may sense colors, spaciousness, or brightness and darkness, this is merely the sensation of the mental consciousness; it is not the true eye consciousness perceiving these scenes. The realms seen in dreams differ significantly from those seen while awake.

For instance, seeing people from past lives or from other worlds cannot possibly be perceived by the eye consciousness. The eye consciousness absolutely cannot see people from past lives or other worlds; if it could, all sentient beings would possess the divine eye (divyacaksus). Without the supernatural power of the divine eye, the eye consciousness cannot see people or objects from past lives, future lives, or other worlds. If the eye consciousness could see them, the eye faculty would be able to directly encounter those form objects. In reality, the eye faculty cannot encounter those form objects; it cannot perceive those form objects. Otherwise, the eye faculty could reach into past lives and other worlds, and the body faculty could also go to other worlds. In fact, the body remains asleep in bed, having gone nowhere.

The dream state is a solitary realm, a dharmayatana (mental object field) manifested directly by the Tathagatagarbha projecting seeds. Only the mental faculty and the sixth consciousness can perceive it, and only the sixth consciousness can truly cognize and discriminate it clearly. The eighth consciousness projects karmic seeds, manifesting the dharmayatana within the dream, because the mental faculty possesses the nature of grasping and clinging. When the mental faculty grasps, the eighth consciousness complies and manifests the dream. The saying "Where there is daytime thought, there is nighttime dream" illustrates this principle precisely: it is due to the thoughts and contemplations of the mental faculty's thought component (caitasika) that the eighth consciousness manifests the dream.