The Interplay Between the Aggregate of Perception and the Aggregate of Mental Formations

Question: It is said that merely hearing about plums, without actually eating them, causes sour water to flow in the mouth. What is the reason for this?

Answer: In the Śūraṅgama Sūtra, the World-Honored One uses this passage to illustrate the illusory and unreal nature of the realm of the mental skandha of conception (saṃjñā). The mental skandha of conception encompasses the knowing and grasping nature of the consciousness-mind, as well as various mental activities such as thoughts, ideas, and concepts within the mental consciousness. Hearing about a sour plum, one becomes aware of the sour plum, and subsequently, thoughts and conceptions arise within the mind—all of this pertains to the mental skandha of conception. The flowing of sour water in the mouth belongs to the mental skandha of volition (saṃskāra). The fact that the mental skandha of conception gives rise to the mental skandha of volition demonstrates the close interconnection and mutual influence between body and mind. The body can influence the consciousness-mind, and the consciousness-mind can influence the body. Changes and operations within the consciousness-mind can affect the body, causing it to undergo alterations.

The Three Transformative Consciousnesses—the Tathāgatagarbha (Ālayavijñāna), the seventh consciousness (manas), and the six consciousnesses—unite to produce and transform all dharmas. The act of hearing about plums arises from the union of the Three Transformative Consciousnesses. The phenomenon of sour water flowing from the mouth also arises from the union of the Three Transformative Consciousnesses. In both phenomena, the Tathāgatagarbha is the same, the seventh consciousness is the same, and the sixth consciousness is the same. The function of these three consciousnesses is present within the mental skandha of conception, and it is also present within the mental skandha of volition. Moreover, the objects of perception (dharmas) that these three consciousnesses apprehend are identical. Therefore, the mental skandha of conception can connect with the mental skandha of volition; the mental skandha of conception can influence the mental skandha of volition. Thus, hearing and mental conception can cause the body faculty (kāyendriya) to produce sour water flowing from the mouth.

The mental consciousness, based on past experiences, knows that plums are sour. Having eaten sour things before, possessing that experience and memory, the mind then produces a sour reaction. These experiences have already been stored as seeds within the Tathāgatagarbha. When someone speaks of plums, the ear faculty and the mental faculty simultaneously correspond to that sound. The ear consciousness and the mental consciousness then simultaneously apprehend its meaning. The mental faculty, via the Tathāgatagarbha, retrieves past information related to plums. This information, through the mental faculty and mental consciousness, then produces an effect on the body, causing the sour water to flow out.