What is a Thought?

Revised January 24, 2019

There are many confusing terms in Abhidhamma like citta and manō which have been differently interpreted in different books. In order to clarify these concepts, I am writing a few posts in “Dhamma Concepts” section under “Mind and Consciousness” starting with:  “Thoughts (Citta), Consciousness (Vinnana), and Mind (Hadaya Vatthu) – Introduction“. I highly recommend reading those, and especially, “Vinnana, Thoughts, and the Subconscious“.

1. In Buddha Dhamma, a thought or a citta (pronounced “chiththa”), is the briefest moment of awareness experienced by a sentient being. In Abhidhamma it says that there are well over billion of citta in the blink of eye.

  • Let us keep in mind that a citta is much smaller than a billionth of a second.

2. A pure citta only has seven cētasika (phassa, saññā, védanā, cētanā, ekaggata, jivitindriya, and manasikāra) in it; see, “Cetasika (Mental Factors)“. Thus it is the purest form a “thought”, but it is too brief for anyone to experience.

  • The first thing to note is that one will never be able to experience a single thought if we mean by a thought to be a citta, even though we say, “I just had a thought”. The briefest awareness that we actually experience is probably a fraction of a second; Scientists say it is about 10 milliseconds. But that 10 millisecond time is mostly spent by the brain in processing the sense input; once that is done, a series of citta with 17 cittas flow in a very brief time (less than a billionth of a second), and that is what is registered in the mind. We will discuss this later in detail.
  • This series of citta with 17 cittas is called a citta vithi (pronounced “chiththa veethi”); see below.

3. Even a single citta has three phases: uppāda (rising), thiti or thithi (reached peak but still changes), and bhanga (dissolution). Thus a citta arises and fades away very fast.

  • Only a Buddha can see such details as I pointed out in the Introduction. Even people with highest abhiññā powers (attained via jhānās) cannot even come close to seeing such details.
  • This is why Abhidhamma is a special section of Buddha Dhamma that needs to taken “as is”, i.e., we just have to believe what the Buddha said. We cannot hope to verify these details by our own experience (for example that there are a certain number of citta in a citta vithi as discussed below). Yet, Abhidhamma is very valuable in clarifying any issue down to the minute detail.

4. A pure citta with 7 cētasika does not last. Even though it starts as such a pure citta, within the duration of the citta itself (less than a billionth of a second), it gets contaminated by either a set of bad cētasika like lōbha (greed), issa (envy) or a set of good cētasika like saddha (faith) and sati (mindfulness).

  • Before it starts decaying, it goes through NINE STAGES to become viññānakkhandhō (this is NOT the aggregate as in the common usage of viññānakkhandha; rather, here the mind has coupled the information in the previous stages of this citta with past viññāna and future viññāna that are in the mind and has made a “composite”).
  • However, the convention is to call this whole process still a citta.
  • All this happens in less than a billionth of a second! This process keeps repeating in the citta to follow and the process is cumulative, i.e., as more and more citta flow by, the  awareness of the event gets stronger, and we actually begin to feel it.
  • It may be a good idea to read about citta vithi before proceeding: “Citta Vithi – Processing of Sense Inputs“.

5. Thus what we experience is the cumulative effect of numerous of citta vithis. That is why the Buddha talked about kandhas (which means “heaps” in Pali or Sinhala) as in “heaps” of  feelings (vedanakkhandha), perceptions (sannakkhandha), volitions (sankhārakkhandha), and consciousness (viññānakkhandha); those are the “heaps” that we actually experience in a “thought”.

  • If citta fly by that fast, and captures six kind of possible “inputs” (through the five physical senses and the mind itself), how do we “experience” seeing, hearing, etc “at the same time” but still sort them out?

6. This is because the mind is the most powerful entity in this world. All five physical senses just provide traces of inputs ( “memory imprints”), and billions of them arise and perish each second. The mind keeps a record of all past events and MAKES A COMPOSITE SENSE EXPERIENCE moment-by-moment.

  • For example when we hear someone say “apple”, even the letter “a” is comprehended by the mind via billions of citta; then “p” is captured, and by that time “a” sound is gone from the ear.
  • We speak (and are able to understand) about 150 words/minute. The minimum “packet of information” that the brain (not the mind) can process is estimated to be about a hundredth of a second (10 milliseconds) by the scientists. This comes about 1-2 letters in such a “packet”.
  • When it has captured the whole word, “apple” (with several “packets”, each of which processed by a series of citta vithi), the mind automatically matches that with all the past memories and instantly produces an awareness or a mental picture of an apple; past memories as well as hopes for future are recalled by the manasikāra cētasika and the citta is “put together” by the cētanā cētasika.

7. The mind can do this because it can process billions of citta vithi per second!

  • The “bottleneck” is the brain, which takes a relatively long time to process a “packet” of information that comes in.
  • Therefore, the mind falls back to the bhavanga state in between the comprehending of information packets. For example, right after receiving the letter “a”, it falls to the bhavanga state and waits until the next packet with “p” comes.

8. Furthermore, the mind is capable of processing multiple inputs (received via the five senses) that are coming in mixed up.

  • For example, after hearing the letter “a” that comes through the ears, the mind may get a “packet” with information about the smell of the apple. But the mind is capable of “sorting out” these different inputs.
  • It is also able to carry out its own mental processes (thinking and coming to conclusions about what is perceived through the five senses by comparing it with past memories) such a fast speed, that it appears to be done in “real time”.
  • There is nothing that is faster than the mind in this world; see, “Amazingly Fast Time Evolution of a Thought (Citta)“. Also, see the previous post, “Citta and Cetasika – How Vinnana (Consciousness) Arises“.

9. Now the mind “knows” what that person was referring to, and has a mental image of an apple with it smell also registered.

  • If someone hears the word, “lemon”, one could even feel the sour taste of lemon; the mind brings it back from the past memories.
  • Even if we see just the outline of a familiar person at a distance, the mind “fills in the blanks” and flashes an image of that person in your mind so you know who it is.

10. One sensory “event” does not happen in one citta. A sensory event from one of the five physical senses is captured by a single citta (say, cakkhudvāra citta for a seeing event), but that information is processed by a string of cittas with 17 cittas in it; this “string of cittas” is called a citta vithi (pronounced “chiththa veethi”). A citta vithi for ‘seeing” is referred to as a citta vithi at the “eye door” or the eye, one for “hearing” occurs at the “ear door” or the ear, etc.

  • When one citta vithi provides a sensory input, that information is then processed by  three citta vithis that involves only the mind; this citta vithi “at the mind door” is variable; it has around 12 citta normally.
  • Thus there are two types of citta vithi involved in processing a sensory input: a long one with 17 citta to CAPTURE an input from one of the five physical senses (pancadvāra)  AND three manōdvāra citta vithi (at the mind door) with about 12 citta.
  • Both types are thus involved in cognition (awareness) processes; there are other processes by the mind that we will discuss later.
  • Only one citta vithi runs at a given time; they do not overlap.

11. Thus it is mind boggling if we try to imagine the frantic pace the mind works at. At this point, it may be a good idea to look at an analogy to simplify things a bit.

  • A movie is generated by a series of static pictures. When a movie is projected on a screen, static pictures are projected at a rate of about 30 frames a second, and we see the movie as a continuous progression of events; if the projection rate is low, we can see it frame by frame or as “packets of information” separately. When we watch the movie, we do not perceive those static pictures or “packets of information”, but we perceive a continuous progression without any gaps.
  • This was described in #4 of the previous post, “Citta and Cetasika – How Vinnana (Consciousness) Arises“.

12. In the same way, when we perceive that our mind is hearing a word, but in reality that word is the result  of many citta vithi originated at the ear door; and the scene that appears simultaneous is the composite of many citta vithi coming through the eye door and none of it happens “at the same time”.

  • Just like the movie projected at 30-50 frames a second, citta vithi are generated at many frames a second. (I had previously mentioned billions of cittas and that is not correct; the flow of citta vithi is subsided by the processing time of about 10 milliseconds needed by the brain to process each each sense input). Thus we feel that we are watching, hearing, tasting, smelling, touching, and thinking all at the same time.
  • To repeat for emphasis: Our minds processes probably less than 100 citta vithi per second. However, each citta vithi with 17 citta (for five sense inputs) or about 10 citta (for mind inputs) and each of those citta vithi take less than billionth of a second. Even though it takes the brain to process a sense input about 10 milliseconds or so, that information is grasped by the mind in less than a billionth of a second.
  • While the brain is processing a sense input, the mind falls back to the bhavanga state.

13. Just like a movie reel, there is actually a tape (not a physical one) that is recorded in the “mind plane”; this is the origin of the “nāma gotta” discussed in, “Difference Between Dhamma and Sankhara“.  That tape is there forever, and allows one with abhiññā powers to look back to any time in the past; see, “Recent Evidence for Unbroken Memory Records (HSAM)“.

  • Therefore in order to verify rebirth or to look at really old memories, all  one needs to do is to develop abhiññā powers! And there are people, including my teacher Thero,  who can do this today.

14. A citta evolves into viññāna and that is actually what we experience; see, “Amazingly Fast Time Evolution of a Thought (Citta)” and “Viññāna – Consciousness Together With Future Expectations“.

  • There is only one citta at a time. But there is memory, as we just discussed. And that memory is normally hidden because the mind is covered up by the defilements, and when one develops abhiññā powers what one is really doing is to clean up the mind so everything becomes clear.
  • One who develops abhiññā powers through anariya jhānās just let the gunk settle at bottom and see just the upper layers; but one who has developed abhiññā powers through Ariya jhānās is doing that by “cleaning up” the gunk so a much more  penetration to deeper past is possible; see, “Solution to a Wandering Mind – Abandon Everything?“.

15. Thus any of individual sense experiences is VERY BRIEF (the duration of a citta vithi). It is the mind that puts everything together and presents us with a “movie like” experience. This is what the Buddha meant when he told Bahiya Daruchiriya: “Ditté ditta mattan, suté suta mattan, muté muta mattan, viññāté viññāna mattan” or “seeing is just a trace of seeing, hearing is just a trace of hearing, enjoying is just a trace of enjoyment, experiencing is just a trace of experience“. 

  • It is the mind (specifically the viññāna kandha or the aggregate of consciousness) that put everything together and present it as a smooth movie-like experience.
  • Here, ditta, suta muta, viññāta mean “seeing, hearing, enjoying (with smell, taste, and touch), and consciousness respectively; “mattan” means “a mātra” in Sinhala or “a trace” in English. Thus “seeing” is just trace of a visual event lasting only a billionth of a second, then it passes away and a new one comes in; there is nothing substantial in it. Mind makes everything appear solid, permanent, and stable. This is the deeper meaning of that verse.

16. If all this appear too technical, do not worry about it. It took me a long time to figure it out and I think I got the final details worked out recently by also combining information from recent scientific studies. The Buddha could not use today’s technical terms, but what he said in summary form is completely compatible with science. But science is still way behind in terms of the bigger picture.

Next, “What is in a Thought? Why Gathi are so Important?“, ………….