Can solitary consciousness leave the body?

The body is a physical body of material form, a material dharma (rūpa); the mind-consciousness is a conscious mind, formless and without marks, not a material dharma. Between the two there is no physical sense of separation or union; "leaving the body" or "being in the body" are both provisional hypotheses and expedient expressions.

Some people, when they attain a slight degree of meditative concentration (samādhi), experience the phenomenon of the conscious mind leaving the body, feeling as if they are outside their body, dully and blankly watching their own body, while the body still carries on the activities of the five aggregates (pañca-skandha). Those without meditative concentration will not have this kind of experience.

When meditative concentration deepens further, the conscious mind can even leave the body to do things. For example, in the Tang dynasty, a Chan practitioner, while sitting in meditation at night, often saw other bhikṣus so hungry they could not straighten their backs. In order for them to cultivate meditative concentration well, he hid his body somewhere the old monk could not see it, and his conscious mind went by itself to the kitchen, stole the rice pot's bottom crust, brought it back to share with everyone, and then his conscious mind returned to his body to continue meditating. In the end, the old monk discovered it anyway. The old monk felt that his attainment was sufficient for him to go live alone in the mountains and spread the Dharma, so he let him leave the monastery.

If meditative concentration is cultivated to the fourth dhyāna, supernatural powers arise, the functions of the conscious mind become stronger, it can leave the body more readily, and can even split into multiple bodies. What is the principle behind a bodhisattva manifesting countless emanation bodies? Each of the countless emanation bodies has its own separate set of six consciousnesses to sustain the activities of a different physical body, while the eighth consciousness (Ālayavijñāna) remains the original single one, and the manas is also the original one—there will not appear one or more additional manas; otherwise it would no longer be one person.

Why can the mind consciousness and the six consciousnesses exist in countless sets distributed across countless physical bodies? Because the six consciousnesses are born from the combined operation of the eighth consciousness and the manas. When meditative concentration is complete, as soon as the manas gives rise to a thought, the eighth consciousness will manifest one or multiple sets of six consciousnesses, vivid and lifelike, acting on behalf of the manas and the eighth consciousness. Therefore, when there is sufficient meditative concentration, once the manas gives rise to a thought, the solitary consciousness (mano-vijñāna-eka-citta) can go out and introspectively observe oneself. I myself have had this personal experience: I felt my solitary consciousness above my own head, watching myself sitting on the bed, just as I was feeling sad inside.

Because the conscious mind is formless and without marks, not a physical kind of existence, its relationship with the physical body is not any kind of physical relationship. Sentient beings cannot understand this relationship; not knowing what form of existence the formless and markless could be, they often mistakenly assume it resides in some part of the body. In fact, the conscious mind is not in any particular part of the physical body; it is not inside, outside, or in the middle of the physical body. Inside, outside, and middle are physical concepts, while the conscious mind transcends physical concepts.