The Medicine Buddha Sutra Proves That the Manas Has a Good-and-Evil Nature.

Original text of the Medicine Buddha Sutra: 像法转时。有诸众生。为种种患之所困。长病羸(léi)瘦。不能饮食。喉唇干燥。见诸方暗。死相现前。父母亲属。朋友知识。涕泣围绕。然彼自身。卧于本处。见阎魔使。引其神识。至于阎魔法王之前。然诸有情。有俱生神。随其所作。若罪若福。皆具书之。尽持授与。阎魔法王。尔时彼王。推问其人。计算所作。随其罪福。而处断之。

Explanation: During the period of the semblance Dharma, sentient beings have meager merit (alpa-puṇya). When the seeds of the evil karma created in past lives and in this life mature, they become trapped by the retributive results of that evil karma: bedridden for a long time, emaciated, unable to eat or drink, with dry throat and lips, seeing everything dim and lusterless, with the signs of death appearing before them. Their parents and family members weep around them. Yet while the patient's body lies in bed, his consciousness is escorted by the black and white impermanence ghosts and fierce ghosts before King Yama. The patient's innate-born spirit (sahaja-deva) then manifests all the sinful and meritorious karma he has created throughout his life and presents it to King Yama. At this time, King Yama interrogates the patient, evaluates the amount of sinful and meritorious karma in the actions he has created, determines his karmic retribution, and decides his destination.

All sentient beings possess an innate-born spirit. This refers to the seventh consciousness, the manas, the governing consciousness that has always existed and never ceased. When the little ghosts of impermanence seize a person, they are in fact escorting the governing consciousness, the manas, before King Yama. Before King Yama, every person's manas automatically manifests the meritorious and sinful karmic actions performed throughout his life. Because King Yama possesses supernatural powers, he knows with his mind the various karmic actions that person has created, browsing through them as quickly as viewing images on a screen, and then King Yama begins the judgment.

This shows that it is the manas that creates sinful and meritorious karma, wholesome and unwholesome karma, and the judgment is a judgment of the manas. The mind consciousness of the person while alive has long since ceased and cannot follow the manas here to King Yama; what accompanies the manas is the mind consciousness temporarily born within the intermediate body (antarā-bhava). This shows that the manas possesses wholesome and unwholesome nature; otherwise, how could wholesome and unwholesome karma arise? At this time the mind consciousness has already ceased and is not functioning; even if it does function, it is merely the runner and helper of the manas, assisting the manas in its tasks. King Yama does not concern himself with the mind consciousness; he seeks only the manas to judge the sinful and meritorious karma and its retribution.

When a person dies, or is half-dead or in suspended animation, the mind consciousness almost entirely ceases to function. No matter the circumstances, the manas is forever the master of sentient beings, the governing consciousness. After death or suspended animation, the manas is drawn by karmic force before King Yama. After King Yama has reviewed the manas's sinful and meritorious karma, he sees that there is still a bit of merit not yet exhausted, and that this person should not yet die; so he sends the person's manas back into the physical body in the world of the living, and the person revives. Revival means the manas has returned into the physical body and then summons the mind consciousness out to be active.

When the King of Yama judges the dead, he knows to seek the dead person's master, not the dead person's assistants and foot soldiers. Debts have their owner, and karma even more so has its owner; only a fool would go looking for subordinates, assistants, errand-runners, odd-job workers, servants, nannies, and the like. Therefore, the manas can create all wholesome, unwholesome, and neutral (avyākṛta) karma; it possesses wholesome and unwholesome nature and has wholesome and unwholesome mental factors (caittas).