This sutta takes place in Sāvatthi, the capital of the kingdom of Kosala. The Buddha was staying in "Jeta's Grove Park," at a monastery which had been donated to the sangha by a rich layman named Anāthapindika.1 He woke up early in the morning and went into the city to beg for alms, but he realized it was too early to ask people for food. Since he had time to kill, he decided to visit a nearby debate hall to see a fellow wanderer he knew named Potthapāda.
This debate hall was in a park named after Queen Mallikā, near a pale moon ebony tree. It seems to have been a popular place for wanderers and religious people to gather and hold lively public debates. At the time, Potthapāda was here with around 300 other people, and they were all having loud, racuous arguments about all sorts of topics which are considered "animal talk" in Buddhism - improper, pointless things that holy people should avoid discussing.2
Potthapāda saw the Buddha approaching, and quickly started trying to silence the crowd. “Everyone be quiet! The venerable ascetic Gautama is coming this way. He praises quiet—if he sees us being gentle and calm, he may come visit us.” He had a question he wanted to ask, and didn't want to risk the loud, pointless chatter turning the Buddha away. Potthapāda greeted the Buddha as he approached. "Welcome, Lord! It's been so long since you've visited the debate hall. We've prepared a seat for you!" The Buddha sat, and Potthapāda joined him, sitting off to the side in a lower seat.
"Potthapāda," said the Buddha, "it seems I interrupted something. What were you all talking about?" Potthapāda dismissed the question, saying, "Oh, nevermind that! It's not important, and you can always catch up on that later. Actually, I have a question for you."
"You see," said Potthapāda, "a few days ago, some disciples from other traditions came here, and they were talking about the complete cessation of perception3, and how it happens. Some of them said, ‘Perceptions arise and pass away without any cause or conditioning. When they arise, a person becomes aware. When they pass away, a person becomes unaware.’ However, others said, ‘No, that’s wrong! The faculty of perception is truly a person’s self. When it comes, a person becomes aware, and when it leaves, a person becomes unaware.’ Others still disagreed with both of these ideas, saying, ‘There are ascetics and Brahmins who are capable of pushing perception into people, making them aware—likewise, they pull it out, making them unaware.’ Finally, some people said, ‘No, it is the gods who manipulate perceptions in this way, not ascetics or Brahmins!’
“While they were arguing, you came to mind, and I thought, ‘oh, if only Master Gautama were here! He would be able to explain what’s true.’ Well, since you’re here now, please answer this for us: how does one attain the complete cessation of perception?”
Before continuing, we should stop here to clarify a few things. It seems that these other disciples had been discussing a type of trance state where one stops perceiving events or experiencing sense activity - presumably, under the belief that achieving such a state allows a person to escape the suffering which arises as a result of the sensory process. There were different beliefs regarding how such a state was achieved - importantly, these different understandings shared one thing in common: one could not stop perceptions on their own.4 Some believed it was entirely up to chance, while others believed they had to rely on some outside entity - whether it be a holy man, or a god - to intervene on their behalf and bestow upon them the cessation of perception.
Potthapāda, then, wanted the Buddha to instruct the assembly in the way to achieve this state, and bring perceptions to an end. The Buddha, quite skillfully, gets to the heart of the answer they seek - how to achieve liberation from suffering - while also demonstrating the ways in which the question being asked is misguided and rooted in misunderstanding.
“First, Potthapāda, let’s address one of those ideas - that perceptions arise and pass away without any causes or conditions. This is completely false. Perceptions arise and pass away exclusively because of causes and conditions!5 In fact, I teach a practice which leads to the cessation of certain (unwholesome) perceptions, while giving rise to other (more wholesome) ones."
Let's stop again, briefly, to contextualize this. The Buddha explained to Potthapāda that perceptions always arise because of causes and conditions, which necessarily negates the first belief about perceptions held by some of the other disciples. He then lays out the religious training he teaches to his own disciples. This training, as opposed to the beliefs of Potthapāda's peers, emphasizes that one has to exert effort and achieve "cessation of perception" by progressing through states of meditation.
However, the Buddha has recontextualized "the cessation of perception" - instead of referring to an ultimate goal of some trance state where no perception of sense activity is possible, the Buddha teaches how to progress through successive stages of meditation where a practitioner slowly abandons perceptions of "lesser" things, while simultaneously cultivating perceptions of higher experiences which gradually lead one closer to enlightenment.
Here, for the Buddha's explanation of this practice, the sutta presents a modified version of the Sīlakkhandhavagga Pericope. It begins with the usual preliminary discussion of the appearance of a Tathāgata in the world, then moves to the discussion of training by introducing a hypothetical person who joins the monastic order and becomes "perfected in ethics." It proceeds as usual up to the discussion of the four jhānas, but in this sutta, the standard formula for the meditative states of absorption is modified in order to emphasize the different types of perception which arise and pass away at each stage.
In the first jhāna, perceptions related to sense-desires pass away, while perceptions of the "unworldly" jhānic feelings arise. These feelings - rapture and bliss - are "unworldly" because they are not produced through sense-contact. In the first jhāna, they arise through withdrawal from sense-desire. These feelings completely fill the body.
These unworldly feelings which can be perceived during the jhānas are pleasurable, but they do not stir the underlying tendency to seek more sense-pleasure the way worldly feelings do. In fact, jhānic rapture and bliss empower us to turn away from the temptations of worldly sense-pleasures.6 In this way, perceptions of lesser things are abandoned, and perceptions of higher things arise.
In the second jhāna, as discursive mental processes come to a stop, the mind becomes more tranquil and unified, and a higher state of concentration is achieved. The previous perception of rapture and bliss from the first jhāna has passed away, and the perception of rapture and bliss born from this concentration arises in its place.
In the third jhāna, the feeling of rapture ceases altogether. The mind grows more equanimous, mindful, and aware. The previous perception of rapture and bliss from the second jhāna has passed away, and the perception of bliss and equanimity arises in its place.
In the fourth and final jhāna, all states of pleasure and displeasure alike are abandoned. Equanimity and mindfulness are fully-realized, purifying the mind and imbuing it with a stability and pliancy which places one in the ideal position to achieve enlightenment. The previous perception of equanimity and bliss has passed away, and the perception of a powerful neutrality - neither-happiness-nor-unhappiness - arises in its place.
The modified Sīlakkhandavagga Pericope ends here. Instead of continuing with the usual list of feats one can achieve by directing the mind while rooted in this highly-cultivated concentration, the Buddha tells Potthapāda about three of the four "formless attainments" (arūpa samāpattis). A detailed description of these states is beyond the scope of this page (and truthfully speaking, beyond my own understanding as well), so let the following suffice: the formless attainments are different states of meditation which the Buddha sometimes taught after the jhānas. They are not necessary for enlightenment, so the Buddha did not always recommend them.7 They correspond to four different planes of rebirth, and seemingly allow the mind to "make contact" with these planes by abandoning all perceptions of form through temporary separation from the five bodily sense-gates.
In fact, these states are also called the arūpa-āyatanas, or "formless spheres," with "spheres" here being the same word applied to the six sense-gates and their corresponding sense-objects. This demonstrates how "set apart" from the senses and ordinary sense-activity these states of meditation are - they are classified in a completely separate domain.8
The first formless attainment is the sphere of infinite space. Here, one passes beyond all perceptions of form and of "diversity" (referring to the 5 kinds of physical sense-activity)9. The perception of the infinitude of space arises. This allows the mind to expand in all directions, unbounded by spatial conceptions of boundaries and directions, which is useful for other practices where one is instructed to extend loving-kindness or compassion in all directions to all living beings. The field of awareness is expanded from an object (for example, the frame of reference used to cultivate mindfulness before entry into the jhānas, such as the breath) to the expansive domain within which any possible object could be conceived.10
The second formless attainment is the sphere of infinite consciousness. The previous perception of the infinitude of space is replaced with the perception of the infinite, unrestricted nature of the very mind which was perceiving that boundless sphere of space.
The third formless attainment is the sphere of nothingness.11 The previous perception of the infinitude of consciousness (or more generally, the mind) is replaced with the perception that "there is nothing (substantial) at all." Or, to put it another way, the perception arises that there is nothing conceivable which has "thing-ness." Perceivable objects, the subjective mind which functions as the vehicle of perception, and phenomena which arise from the interaction between them alike are devoid of any persistent, enduring nature. Conceptual distinctions between one thing or another are abandoned. Instead of "things," there are "events" in the causal process and the mind no longer bothers to project concepts onto these events. Because of this insubstantiality, perception conceives that there is nothing in the field of experience which can be grasped, or to which one can be attached.
In Buddhist teachings, there is a fourth formless attainment, but this sutta stops short of it.12 Instead, the Buddha emphasized to Potthapāda the fact that one must deliberately "take responsibility" for the function of perception for themselves, instead of relying on chance, or the intervention of gods or holy men. Following the Buddha's training, as he had laid out thus far, takes one to "the peak of perception." With the attainment of the sphere of nothingness, perception has been refined to such a subtle level that it is no longer beneficial to further cultivate. Realizing this, one stops and thinks, "continuing to direct my mind in this way won't do any good - there are no further subtle perceptions which may arise, so continuing to exert effort will only give rise to the coarse perceptions I had previously abandoned. Instead, I must stop directing my mind altogether." The practitioner here stops attempting to direct their mind and simply allows it to abide in the stability of the meditative attainment which has been reached at this point.
This allows the mind to settle in the state of "nirodha," or "cessation," and in this context refers specifically to the cessation of perception. The previous perception of the sphere of nothingness passes away, but nothing arises to replace it. "This training, Potthapāda, is how one achieves the cessation of perception."
Having concluded his description of the gradual training, the Buddha stopped and asked Potthapāda if he had ever heard the cessation of perception explained in this way. "No, Lord, I have not. As I understand it..." Potthapāda repeated everything he had heard, and the Buddha confirmed that he had correctly understood the message.
"Lord," Potthapāda asked, "when you speak of this 'peak of perception,' is it just one? Or are there many such peaks?" The Buddha replied, "It can be understood in both ways. I describe the peak of perception according to whichever level of attainment someone has reached; at each stage, perception is, on some level, brought to an end." This point is confusing, but I take it to mean that the Buddha simply acknowledged that each stage in the progressive path of meditation culminates in a point where certain perceptions are abandoned, and in that sense, there can be many smaller "peaks," or plateaus (to expand on the metaphor), while still ultimately leading to the ultimate "summit" of "complete cessation" after the third formless sphere.
Next, Potthapāda wanted to know about the relationship between perception and knowledge. "Which arises first, Lord: perception, or knowledge? Is it possible they arise at the same time?" The Buddha answered, "Perception arises first; its arising conditions the arising of knowledge."
I think this can be understood in two ways. First, and most straightforwardly, in the Buddhist understanding of the sensory process, perception of a sense-object necessarily arises before one could be said to "know" it. It is this very faculty of perception which serves to interpret and identify sense-objects by grasping its "signs," allowing us to think and ponder them.
Secondly, on a more philosophical level, one must rely on the faculty of perception in the practice of meditation and establishing mindfulness in order to progress through the states which lead to liberating insight.
Next, Potthapāda asked a short, but incredibly important, question: "Is this faculty of perception a person's Self? Or are perception and the Self two different things?"13
The Buddha must have recognized what a problem Potthapāda's clinging to the idea of a "Self" presented, because he stopped to change directions and tackle this new issue. "Potthapāda, do you believe in a Self?"
"Yes, Lord; I believe in a material Self, composed of the four great elements14 and sustained by solid food." In response, the Buddha said, "Very well - for the sake of argument, let's assume such a Self exists. Perception could not be this self... as we have discussed, perceptions arise and pass away as a result of causes and conditions. How could something which behaves that way be the Self?"
Potthapāda considered this, and amended his answer: "Then, there is a mind-made Self, complete in all its parts, not lacking in any sense faculty." The Buddha repeated his previous critcisim, and once more, Potthapāda suggested the existence of a formless Self, made up only of perception itself. The Buddha objected yet again on the same grounds.
Potthapāda was confused. All three ways in which he could imagine the Self were incompatible with what the Buddha had taught him about perception. "Lord," he asked, "is it possible for me to know whether or not perception is the Self?" The Buddha reassured him, "It's no wonder this is a difficult topic for you - the background from which you come, and the tradition you have been taught, make it hard to understand."
Potthapāda gave up on the topic of the self for the time being.
Next, Potthapāda began asking the Buddha a series of 10 questions which the Buddha, on principle, refused to answer at many points throughout his career. Walshe suggests that these questions were common talking points among religious wanderers in the Buddha's time, perhaps used as a means of testing one another. The Buddha felt that they were a waste of time, because their answers would not bring anyone closer to enlightenment. The 10 questions are as follows:
After each question, the Buddha simply said "I have not declared these things one way or another." When Potthapāda asked why, the Buddha explained that these questions are pointless philosophical exercises and do nothing to aide one along the path to enlightenment.
Puzzled, Potthapāda asked, "Well, what things do you declare for certain?" The Buddha stated plainly, "I teach the truth of dukkha. I teach the truth of dukkha's origin. I teach the truth of how dukkha is ended. I teach the truth of the path which leads to the end of dukkha." Potthapāda asked, "Why do you declare these things?" The Buddha replied, "I only speak about things which are conducive to enlightenment; these things, Potthapāda, are conducive to enlightenment."
Potthapāda proclaimed, "Yes! Great! What you've said is certainly true, Lord. I suppose I've kept you here long enough, though - please feel free to go about your business." With this, the Buddha stood up and took his leave, presumably to begin his alms-round.
After the Buddha left the debate hall, the other people began relentlessly teasing Potthapāda. "You're such a kiss-ass! Anything that Gautama fellow says, you eat it up. 'Oh, how true! You're so right!' What a joke. None of us even know what his teaching is, because he refuses to answer so many questions!"
Potthapāda said, "Look, I'll admit, I don't really understand why he won't answer those questions myself... but I know this for certain: that Gautama teaches a doctrine rooted in truth. Why wouldn't I praise the things he said?"
A few days later, Potthapāda went to visit the Buddha once again, this time bringing Citta Hatthisāriputta ("Citta, the son of an Elephant-Trainer") with him. Citta bowed and sat to the side. Potthapāda exchanged polite greetings with the Buddha, took a seat with Citta, and told the Buddha what happened after he left the debate hall.
“Potthapāda, those men are fools. You alone understand—some things I declare, and some things I don't.” He repeated the ten points and once more explained why he refused to answer those questions. He also repeated the things which he did declare definitively: the Four Noble Truths. Likewise, he repeated his reason for declaring these teachings.
“Potthapāda, some people claim that there is a self, and after death, that self is happy and healthy. I ask them, ‘Do you know of any world which is perfectly happy?’ Of course, they don’t know of any such world, so I ask them: ‘Have you ever experienced one single day—or even a half of a day—in which you were perfectly happy?’ Of course, they have never experienced such a day, or even half of such a day, so I ask them: ‘Do you know of a path or practice which allows you to achieve a world that is perfectly happy?’ Of course, they don’t know of any such path, so I ask them: ‘Have you ever heard the voices of joyous gods, who have been reborn into a perfectly happy world, declaring that it is possible to achieve perfect happiness through following some path or practice?’ Of course, they’ve never heard any gods saying such things.
“Don’t you agree, Potthapāda, that it’s stupid for people to claim that there is a self which is perfectly happy after death, with absolutely no basis for such a belief?” “Yes, lord.” “It’s like a man professing his undying love for the most beautiful woman in the land - but, when questioned, he is unable to say what caste she comes from, or what her name is, or what clan she belongs to, or what she looks like, or where she lives. Wouldn’t that be stupid, Potthapāda?” “Yes, lord.” The Buddha repeated himself, but this time with a different similie. “It’s like a builder constructing a staircase for a palace he knows nothing about. Wouldn’t that be stupid, Potthapāda?” “Yes, lord." The sutta repeats this passage yet again.
"Potthapāda, because of rebirth, it is possible to speak of three kinds of "Acquired Self." There is the Material Acquired Self, the Mind-Made Acquired Self, and the Formless Acquired Self.15
"The Material Acquired Self is made of form, composed of the four great elements, and is nourished by solid food." This corresponds to the lowest sphere of rebirth in Buddhist cosmology: the World of Sense-Desire (Kāma-loka). The types of rebirth which fall under this classification cover a wide range of beings, including those reborn in hell-realms, spirits, animals, humans, and lesser gods. The beings in the World of Sense-Desire are, by default, characterized by desires of the five physical senses.
"The Mind-Made Acquired Self likewise is made of form, but it is produced spontaneously by the mind - it is complete in all its parts, not deficient in any sense faculty." This corresponds to the middle sphere of rebirth: the World of Form (Rūpa-loka). Sometimes this is translated as the "Fine-Material" World, referencing the fact that beings here - various classes of gods - are still understood as having a physical form, but it is more subtle than the relatively more gross bodies possessed by the beings of the World of Sense-Desire. In the World of Form, beings are "Mind-Made," meaning that they are not born through sexual reproduction; instead, they arise spontaneously as a result of mental activity. People who have achieved the jhānas may be reborn in this sphere upon death.
"The Formless Acquired Self is not made of form. It is made from perception (of the Formless Attainments)." This corresponds to the highest sphere of rebirth: the Formless World (Arūpa-loka). Here, there is no physical matter. Beings exist only on a subtle mental level. People who have achieved the formless attainments may be reborn in this sphere as higher gods.
The Buddha continued, "I teach the path which leads to the abandonment of rebirth with the Material 'Acquired Self.' If you follow this path, defiled states are abandoned, and purifying states are cultivated. You will enter and abide in perfect wisdom, having achieved this by way of your own insight, in this very lifetime." In other words, the Buddha said that following his teaching can lead one to enlightenment, which ends the cycle of death and rebirth.
"Potthapāda, you may think that abiding in this way is still dukkha.16 Do not make this mistake. Abiding in the way I have taught leads to joy, rapture, peacefulness, mindfulness, and awareness - abiding in this way is truly blissful. The Buddha repeated these statements for the other two forms of "Acquired Self."
"Potthapāda, someone may ask us, 'What is the Material Acquired Self, the one you speak about abandoning?'17 We should tell them, 'it's simply this very material self before you.'" In other words, there isn't some secret, eternal Self hidden away somewhere waiting to be discovered. Any "Self" which can be said to exist is directly observable, and exists merely as a product of Dependent Origination.
Again, the sutta repeats these points for the other two forms of Acquired Self.
The Buddha asked, “What do you think, Potthapāda? Isn’t this sensible?” (as opposed to the belief in a Self which experiences happiness after death) Potthapāda agreed.
Citta spoke up for the first time. "Lord, when one can be said to have a Material 'Acquired Self,' what can be said of the other two kinds? Can they be said to exist as well, or is it only the material one which could be said to exist at that time?"
"Citta," the Buddha answered, "when one presently has a Material 'Acquired Self,' it cannot be described as 'Mind-Made' or 'Formless.' It can only be called 'Material.'" He repeated this statement for the other two kinds.
Continuing, he said, "Think of it like this. Imagine if someone asked you these questions: 'Did you exist in the past? Will you exist in the future? Do you exist now?' How would you answer, Citta?"
"I suppose I would say, 'I existed in the past. I will exist in the future. I do exist now.'"
"Now, imagine they next asked you these questions: 'Was your past self the true one, with the other two being false? Or will your future self be the true one? Or could it be that the Citta which exists now is the true self, with both past and future existences being false?'"
"Well, I would say, 'In the past, my past self was true. In the future, my future self would be true... and right now, this self which exists is true."
"Yes," said the Buddha, "and in just the same way, when one has acquired one type of self in a particular lifetime, there's no reason to discuss the other two. Let's consider a cow's milk: it can be churned into butter, and that butter can be used to make ghee. Ghee, itself, can be used for cream of ghee. However, when we have one specific type of these dairy products, there's no sense in speaking of it in terms of the other forms. When we have milk, we do not ask if it is curds, or ghee, or cream of ghee."
The Buddha stopped to make something clear. "However, Citta, it is necessary to understand something: these are merely worldly terms and expressions meant to help you understand the more subtle idea. A Tathāgata speaks in this way in order to help worldlings understand these things, but does not grasp them or misunderstand them." Walshe points out that this is an instance of the Buddha acknowledging an idea known in Buddhism as "the two truths." There is "conventional truth," founded on plainly observable realities and utilizing mundane vernacular, which the Buddha must rely on in order to express ideas to people. Then, there is "ultimate truth," which reflects things as they truly are, but cannot always be parsed in words - especially to the unenlightened, who are still bound by the cycle of dukkha (which begins with ignorance).
Potthapāda was delighted, and declared himself a lay follower of the Buddha. Citta was likewise elated, but he requested to ordain as a monk. The Buddha gave him his vows on the spot, and the sutta tells us that shortly thereafter he achieved enlightenment while practicing meditation in solitude.
The corresponding sutra from the Chinese Canon is Dīrghāgama 28. I do not have access to an English translation of this sutra. I will update this section if I ever get the chance to read it.
 In the Buddha's lifetime, this was one of the most important monasteries. During India's rainy seasons, the Buddha and his sangha would stop travelling and enter retreat somewhere, and this monastery was where the Buddha stayed most often. The suttas tell us generally about how Anāthapindika (then known as Sudatta) met the Buddha, converted, and spent lots of money on building this headquarters for the Buddha's order.
The Vinaya elaborates on this story. After meeting the Buddha, Anāthapindika is said to have started searching for a peaceful place to build the monastery he was planning on offering to the sangha. Eventually, he found a forest grove which belonged to Prince Jeta, one of King Pasenadi's sons. He went to prince's palace in order to ask how much it would cost to buy the grove. The prince said that 18,000,000 gold coins would be the appropriate value, but he was not willing to sell it for even that much, despite Anāthapindika offering to pay it on the spot. They consulted a middle-man, and he appraised the property as being worth however many gold coins it would take to physically cover every bit of ground in the grove. Anāthapindika had gold coins wheeled out in carts, and he had almost every square inch of ground covered - only one small bit of land near the entrance remained. Determined, Anāthapindika ordered for more gold to be brought, but Prince Jeta stepped in and said there was no need. He had been so moved by Anāthapindika's commitment and devotion to acquire this offering for the Buddha that he decided that last piece of gold was unnecessary. In addition, he was going to personally pay for a grand gate and tower to be built, further insulating the property from the outside world for the sake of the sangha's meditative practice.
I'm not sure how much stock should be put in the historicity of this story, but it's amusing, so I included it here.
 Specifically: discussions about kings, criminals, and ministers; about armies, dangers, and war; about food, drink, clothes, and beds; about garlands and perfumes; about families, carriages, and territories; about women and heroes; gossip (“street-talk and well-talk”); speaking about the dead; random, pointless chatter; tall-tales about land and sea; and finally, talk about being reborn in one way or another.
 "The complete cessation of perception" is translated from an obscure Pali term, "abhisaññanirodha." Sarah Shaw, in her book "The Art of Listening," notes that this sutta features its only occurrence in the entire Pali Canon - this is also the earliest record of the term in all of Indian literature. It's no surprise that there’s room for debate on how it should be translated. Literally, it means “the higher/complete cessation of perception.” “Abhi” usually means “higher” or “complete,” as in a more advanced version of something. However, Piya Tan quotes the commentary in claiming that, in this instance, “abhi” means “concerning.” I don’t understand what this would mean. “Higher” makes more sense to me.
Walshe quotes the Pali-English Dictionary in pointing out that “saññanirodha” (literally “the extinction of perception”) was an expression used by non-Buddhists to refer to a type of trance. John J. Holder, in "Early Buddhist Discourses," suggests that the people who used this term believed that achieving this trance state would lead to the end of suffering.
So, there is some disagreement as to what exactly "abhi" means here, but ultimately it's a minor point. The usual translation of "higher" or "complete" works just fine and makes plenty of sense. There is generally a consensus that "saññanirodha" is a non-Buddhist compound word referring to a state of trance. However, the exact meaning of the word "sañña" here is a more complicated issue.
Piya Tan argues that, in this instance, “sañña” is best translated as “consciousness” instead of the more usual “perception.” Accordingly, he uses “consciousness” for other instances of “sañña” throughout the sutta. Walshe translates “abhisaññanirodha” as “the higher extinction of consciousness,” and similarly notes that “sañña” in this sutta is best understood as meaning “consciousness,” although he reverts to using the more usual translation “perception” for other instances of “sañña” in the sutta (for the sake of simplicity, I assume).
Holder, however, translates the term as “the complete cessation of perception.” He also notes how the term refers to a trance state, but insists that “perception” is still an apt translation for “sañña” because in this state of trance, the person would be aiming to stop perceiving anything.
I follow Holder’s example in this synopsis, primarily because it’s the simplest explanation. It makes the most sense when I look at the way “sañña” is used throughout the sutta. Thanissaro Bhikku and Bhikku Sujato also use the translation “perception” in this sutta, reinforcing this decision. Still, I wanted to make sure readers were aware of the other possibility as well.
 This was pointed out by Sarah Shaw in her book "The Art of Listening."
 Here, the Buddha is noting that perceptions - like all conditioned things - arise and pass away as a result of Dependent Origination.
 For a detailed look at why spiritual feelings have this empowering effect, look at the works of Keren Arbel, such as this essay and her book "Early Buddhist Meditation: The Four Jhānas as the Actualization of Insight." To see this mentioned in the canon, check MN 14, MN 44, and DN 34 (for starters - there are other such references throughout the suttas).
 Some places in the canon (such as MN 111 & 121) show enlightenment being achieved after the formless attainments. However, the formula of enlightenment following the jhānas is far more common, and demonstrates that the formless attainments are not necessary to achieve enlightenment, even if they are helpful.
 Sarah Shaw, "The Art of Listening"
 SN 14.7 suggests that "the perception of diversity" includes all six sense sense-spheres, but MN 43 seems to specify that, in the context of the formless attainments, it is the five physical sense-spheres which are abandoned.
 The two preceding points are not mentioned in the sutta, but are raised by Sarah Shaw in "The Art of Listening." The other points about these formless spheres should likewise be attributed to her.
 This can be a source of great confusion. Most translations render the Pali term "Ākiñcaññā" straightforwardly as "nothing," as in, the absence of anything. I think any fair survey of the suttas shows this isn't a great reading. For example, MN 106, MN 111, and AN 9.36 indicate pretty clearly that some things can still occur or be contemplated within this sphere. Instead, I follow Sarah Shaw (again, I direct you to her book "The Art of Listening") and Michael M. Olds (I direct you here and here.
 The reason for this, I assume, is because the 4th formless attainment is "the sphere of neither perception or non-perception," and would thus go beyond the scope of the Buddha's intended message here (focusing on explaining the function of perception during meditation). As he explains, the "peak of perception" is reached in the 3rd formless sphere.
 In his translation, Walshe points out an amusing note to this passage from the commentary: essentially, it says that Potthapāda, mired in delusion as he is, couldn't resist turning back to the idea of a "Self," even after this incredibly profound teaching from the Buddha, in much the same way that a pig can't resist rolling around in shit, even if it's adorned with perfume and fine jewelry. It's funny, but it also goes to show how insidious the belief in a "Self" is - it has the potential to completely undermine our understanding by rearing its ugly head.
 For more information on the different ideas of "the Self" in the Buddha's time, see DN 1 and my summary of the fundamental teachings.
 The Pali word for "acquired Self" is atta-patilābha, which translates to something like "the adoption of a Self." Sujato liberally translates the term simply as "rebirth," which gets to the heart of the point the Buddha is making - this is why I added the term "rebirth" to the Buddha's statement here. Walshe cites Rhys Davids in giving a more detailed explanation: "the fleeting union of qualities that make up, for a time only, an unstable individuality." Furthermore, Walshe points out that these three kinds of “acquired self” correspond to the “3 realms” of rebirth (the realm of sense-desire, the realm of form, and the realm of formlessness). The point here is this: we may only speak of "a Self" as a temporary nexus of phenomena which exists as a result of Dependent Origination.
 Here, Walshe speculates that the Buddha was alluding to a common misconception that practicing these advanced meditations are boring and unpleasurable. I think it's more likely that the Buddha was saying enlightenment puts an end to all dukkha. One way or another, it's clear that the Buddha wanted to emphasize that enlightenment involves incredibly subtle, highly-refined states of pleasure which aren't even comparable to lesser worldly pleasures. See SN 36.31.
 This part of the sutta reproduces a lot of previous passages. For the sake of brevity, I've ignored most of these repetitions, only mentioning them when it seems pertinent. It also repurposes the staircase metaphor from earlier, this time used to demonstrate the logical consistency of the Buddha's teaching as opposed to the baseless beliefs about the Self. I've left this out as well.