Citta Vithi – Fundamental Sensory Unit

 January 6, 2021; revised January 10, 2021 (#9)

 Citta vithi is the smallest sensory unit that is experienced by the mind. It is a series of citta with 17 citta for a pañcadvāra citta vithi. A manodvāra citta vithi can have a variable number of citta.


1. This subsection is a continuation of the series of posts in “Buddha Dhamma – A Scientific Approach.”

  • In this bottom-up analysis, we will get to the fundamentals of Buddha Dhamma. That involves tackling some basic features of Abhidhamma. Thus it will require some effort.
  • But it will be a rewarding experience for those who make an effort.
  • Buddha Dhamma can be understood via the Four Noble Truths or Tilakkhana or Paṭicca Samuppāda. If one understands any one of those three, one would understand all three.
  • Our approach here is to look at the fundamental processes involved in a sensory event. That will provide invaluable insights to Paṭicca Samuppāda.
A Citta Lasts Only a Billionth of a Second

2. What we call a “thought” is the cumulative effect of billions of cittā flowing through a mind. The mind — which processes cittā — is the fastest entity in the world (Ref. 1)

  • Furthermore, a single citta does not arise in isolation. A citta ALWAYS arise in a citta vithi (series of cittā), some with 17 cittā; see below. Billions of such citta vithi can flow through a mind in a second. What we “feel” is the cumulative effect of billions of such citta vithi.
  • When exposed to a new ārammaṇa (new sensory input), the first series of citta vithi arises without even being aware. We will start experiencing them within a short time, and when we do, we CAN have control over the SUBSEQUENT citta vithi related to those that arose first.
  • But if we don’t pay attention, such citta vithi can progress on their own and induce us to speak badly or even do bad things.
  • That is why the need to be “mindful.” 
  • For example, when someone says something nasty, we may automatically respond with bad speech or even bodily actions. Some people are prone to do that more than others. But ANYONE can cultivate mindfulness and be able to have control over one’s speech or actions. Of course, it will take time to cultivate mindfulness. Our analysis here will help understand that process too.
Roles of Arammana and Gati in a Sensory Event

3. To emphasize, we DO NOT have control over how citta vithi first arise due to new sensory input. They arise AUTOMATICALLY based on two things: The particular ārammaṇa (sense object) and one’s habits/character (gati.) Note that “gati” is pronounced “gathi” as in “Thailand.” That is easier to explain with a few simple examples.

  • Consider a husband who likes alcohol and his wife, who dislikes alcohol. A friend visits them and brings a bottle of alcohol.
  • That bottle of alcohol is the ārammaṇa. When the husband sees it, he feels happy. His wife sees the bottle at the same moment and becomes unhappy. Therefore, that same ārammaṇa induced different types of citta vithi in the husband and the wife’s minds! That means different types of cetasika (mental factors) arise in the citta in those two types of citta vithi.
  • Prior experiences of the husband with alcohol are “happy occasions” for the husband. He has a gati to be attracted to alcoholic drinks. On the other hand, his wife cannot even stand the smell of alcohol, and she believes alcohol is bad to drink.
  • However, gati can change. At a later time, the husband may give up alcoholic drinks after seeing the bad consequences of drinking. It is also possible that the wife may start associating with a group of friends who drink alcohol and gradually begin to form a liking for alcohol taste.
  • See Ref. 2 for details on the critical roles of ārammaṇa and gati.
One Sensory Unit (Citta Vithi) At a Time – But They Flow Incredibly Fast

4. Let us consider that sensory event of “seeing a bottle of alcohol” when a friend brings that bottle. Let us consider the thoughts that flow through the husband’s mind at that time of the visit.

  • At the time of seeing the bottle, he is likely to be talking to that friend. It appears that talking, hearing the friend’s words, and seeing the bottle in the friend’s hands all happen simultaneously.
  • They may happen at ABOUT the same time. But even just two sensory events CANNOT happen simultaneously (say, hearing the friend say “hello” and seeing the bottle in his hands).
  • Hearing his friend say “hello” happens with a citta vithi of 17 cittā. That auditory sensory input comes through the ears. It is a sotadvāra citta vithi.” The sensation of “hearing” or sota viññāna arises in such a sotadvāra citta vithi.
  • Seeing the friend with the bottle happens with a TOTALLY DIFFERENT citta vithi triggered by the visual event coming through the eyes. It is a cakkhudvāra citta vithi.” The sensation of “seeing” or cakkhu viññāna arises in such a cakkhudvāra citta vithi.
Mind Can Process Numerous Citta Vithi Very Fast

5. A given citta vithi is based on ONE ārammaṇa. Until that series of citta run its course, another citta vithi WILL NOT start.

  • In the above example, hearing the sound “hello” was based on one citta vithi. The sight of the friend was with another citta vithi. But since they happened so fast that one would think they happened simultaneously.
  • Countless citta-vithi involving ALL SIX senses can flow alternatively in a split-second!
  • The mind is capable of “sorting out” different types of ārammaṇa (sights, sounds, smells, etc.) That is why the Buddha said that the mind is the fastest entity in the whole world.
  • Because these citta-vithis flow VERY FAST, and the mind can keep up with fast processing, we feel as if they all happen simultaneously! For details, see Ref. 3.
Each “Data Packet” From a Sense Door Analyzed by a Citta Vithi

6. As discussed in Ref. 3, the following sequence of events happens before we experience a sensory input. Consider seeing the bottle of alcohol in the above example. (1) Eyes capture the scene of the friend holding the bottle. That captured frame is of about 10-millisecond duration. (2) That signal is sent to the brain via the optic nerve. (3) Brain processes that “data packet” and transfers to the gandhabba’s “invisible body.” (4) That signal is transferred to the “cakkhu pasāda rupa.” (5) The cakkhu pasāda rupa transfers the signal to the hadaya vatthu (seat of the mind.”)

  • We also discussed the above aspects briefly in #7 and #8 of Ref. 4. Now, let us see in a bit more detail what happens when the cakkhu pasāda rupa hits hadaya vatthu and transfers the signal to hadaya vatthu.
  • The best way to understand this process is to visualize the hadaya vatthu surrounded by five pasāda rupa. Only one pasāda rupa can “hit” (or make contact) with the hadaya vatthu at any given time.
  • Of course, those entities (pasāda rupa and hadaya vatthu) can never be seen, even by the most sensitive instruments. Thus, the following is just an analogy to visualize the process easier.
The “Bell Analogy”

7. Imagine a big metal ball (hadaya vatthu) surrounded by five smaller balls (five pasāda rupa.) When one smaller metal ball hits the big metal ball, that big metal ball will “ring” (vibrate) a certain number of times. For a pañcadvāra citta vithi, that number is ALWAYS 17.

  • This is similar to the “ringing” of an old fashioned bell (like the Liberty Bell in Philadelphia) when hit by a metal object.
  • In fact, Buddhist temples have bells that were originally designed to convey this idea of a citta vithi: One pulls a rope tied to a small metallic ball inside a metal dome so that the metal ball hits the dome, and that emits a “ringing sound.”
  • At the very fundamental level, such a “contact” of a pasāda rupa with hadaya vatthu is the only brief moment of sensory experience! (see Ref. 5.)
  • The Pāli word “phassa” represents that “contact.” 
Phassa– Contact Between a Pasāda Rupa and Hadaya Vatthu

8. Therefore, that “contact” (phassa) DOES NOT happen, for example, between the physical eyes and a physical object (rupa.) First, the brain processes that picture captured by the eyes and transfers it to the cakkhu pasāda; See Ref. 4. It is only then the cakkhu pasāda transfers that signal to hadaya vatthu by “hitting” the hadaya vatthu (just like the dome of a bell getting hit by a metal ball.)

  • This is what is meant by the Pāli term “phassa.” For example, in the Pāli verses, “salāyatana paccayā phasso” and “phassa paccayā vedanā” refer to the “contact of an external sensory input with the mind (hadaya vatthu)” and “that contact leading to experiencing the sensory input.”
Contact (Phassa) by a Pasāda Rupa Makes Hadaya Vatthu Vibrate 17 Times

9. When the hadaya vatthu is “hit” by a given pasāda rupa (i.e., when it transfers the sensory signal to hadaya vatthu,) that leads to 17 vibrations of hadaya vatthu; no more and no less. That is a citta niyāma or a universal law. With each “vibration,” the hadaya vatthu generates a citta.

  • That is the origin of a citta vithi with 17 cittā (“thought moments”) in a sensory event involving pañcadvāra or the five physical doors (eyes, ears, nose, tongue, body.) 
  • The duration of those 17 thought-moments is how long that sensory experience lasts in reality (see ref. 5). It is a billionth of a second! Of course, billions of such citta vithi flow through the mind it appears to us as if we are continuously experiencing it. But the mind falls to the bhavaṅga state numerous times in between those citta vithi.
  • Note that a pasāda rupa plays a role ONLY in signals coming through the pañcadvāra (five physical senses), i.e., the rule of 17 cittā per citta vithi holds ONLY for pañcadvāra citta vithi.
Manodvāra Citta Vithi Do Not Have the 17-Citta Limit

10. When a dhammā comes to the mind or hadaya vatthu (via the mana indriya in the brain,) there is no pasāda rupa involvement. That signal goes directly to hadaya vatthu. Furthermore, the “17-citta rule” does not apply to manodvāra citta vithi. They can have ANY number of citta, usually more than 10 cittā.

  • For example, in jhāna samāpatti, manodvāra citta vithi can run for many hours continuously (as long as one is in that samāpatti.)
  • But when in a “regular jhāna,” there could be pañcadvāra citta vithi running between manodvāra (jhānic) citta vithi. That means one could hear external sounds, for example, while in a regular jhāna.
  • But when in a jhāna samāpatti, that jhānic citta vithi runs continuously. Pancadvara citta vithi do not get a chance to “interfere.” Thus, when one is in a jhāna samāpatti, one is totally oblivious to what happens around him/her.
Citta Vithi – Building Block of Thoughts

11. It is a good idea to get some familiarity with citta vithi. That will make it easier to understand future discussions and get a deeper insight into Paṭicca Samuppāda. Further details on citta vithi in the post, “Citta Vīthi – Processing of Sense Inputs.”

  • Of course, the descriptions of citta vithi is not in the Sutta Piṭaka but the Abhidhamma Piṭaka. The easiest way to review my description above is to consult Bhikkhu Bodhi’s “A Comprehensive Manual of Abhidhamma” (Ref. 6.)
  • However, the explanation in #6-#8 is not in Bhikkhu Bodhi’s book. That explanation was based on Waharaka Thero‘s discourses and my own incorporation of current scientific knowledge. I have explained that approach in “Interpretation of the Tipiṭaka – Gandhabba Example.”

1.  Buddha said it is hard to find any phenomena in this world that change faster than the mind: “Aṅguttara Nikāya (1.48)“.

The short sutta says: “Nāhaṃ, bhikkhave, aññaṃ ekadhammampi samanupassāmi yaṃ evaṃ lahuparivattaṃ yathayidaṃ cittaṃ. Yāvañcidaṃ, bhikkhave, upamāpi na sukarā yāva lahuparivattaṃ cittan”ti.”

Translated: “I consider, bhikkhus, that there is no phenomenon that comes and goes so quickly as citta. It is not easy to find an analogy (a simile) to show how quickly citta can change.”

2. “Ārammaṇa Plays a Critical Role in a Sensory Event.”

3. “Vision Is a Series of “Snapshots” – Movie Analogy.”

4. “How Do We See? – Role of the Gandhabba.”

5. This is the very brief sensory experience that the Buddha explained to Bāhiya Dārucīriya with the verse, “diṭṭhe diṭṭha mattaṃ bhavissati.” It means, “what is seen is seen only for a brief moment.” Mattaṃ is “mātra” in Sinhala or Sanskrit or a “trace of something.” What we feel is the cumulative effect of such a large number of contacts that take place in a short time. Yet, the “real experience” lasts only a billionth of a second! See “Does any Object (Rupa) Last only 17 Thought Moments?

6. Bhikkhu Bodhi, “A Comprehensive Manual of Abhidhamma.” This downloadable version is from Pariyatti. The above material is discussed in detail in Chapter IV (p. 149.)

Other posts in this subsection are at, “Understanding the Terms in Paṭicca Samuppāda.”

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