Dighanikaya 22: 9. Mahāsatipaṭṭhānasuttavaṇṇanā

Explanation of the Exposition Section

"Thus have I heard": this is the Mahāsatipaṭṭhāna Sutta. Here, this is the explanation of the unfamiliar terms: "This is the direct path, monks": why did the Blessed One deliver this discourse? Because the inhabitants of the Kuru country were capable of receiving a profound teaching. For the monks, nuns, male lay followers, and female lay followers inhabiting the Kuru country, on account of the excellence of the climate, food, and other conditions in that country, were always sound in body and sound in mind through resorting to a wholesome climate and suitable requisites. Their power of wisdom being supported by the soundness of their minds and bodies, they were capable of receiving profound discourse. Therefore, seeing this capacity of theirs to receive a profound teaching, the Blessed One delivered this Mahāsatipaṭṭhāna Sutta of profound meaning, having cast the meditation subject into arahantship at twenty-one places. For just as a man, having obtained a golden basket, might put various flowers into it, or having obtained a golden casket, might put the seven jewels into it, so too the Blessed One, having obtained an assembly of inhabitants of the Kuru country, taught a profound teaching. For that very reason, he also taught other discourses of profound meaning here: in this Dīghanikāya, the Mahānidāna; in the Majjhimanikāya, the Satipaṭṭhāna, the Sāropama, the Rukkhopama, the Raṭṭhapāla, the Māgaṇḍiya, and the Āneñjasappāya.

Moreover, in that country the four assemblies by their very nature dwelled devoted to the practice of the development of the foundations of mindfulness; even down to the slaves, workers, and servants, they spoke speech connected only with the foundations of mindfulness. Even at places such as water wells and thread-spinning places, no useless talk went on. If some woman, asked, "Lady, which development of the foundations of mindfulness do you bring to mind?", should say, "None at all," they would rebuke her: "Shame on your life! Though living, you are like one dead!" Then, having admonished her, saying, "Do not do so again!", they would have her learn one or another foundation of mindfulness. But when one said, "I bring to mind such-and-such a foundation of mindfulness," they would applaud her, saying, "Well done, well done!", and praise her in such terms as: "Your life is well lived! You have truly attained human status! For your sake the fully awakened Buddha arose!" And not only were human beings here engaged in the attention to the foundations of mindfulness, but even the animals living in dependence on them were as well.

Here this is the story: A certain dancer, it is said, went about training a young parrot. Having lived near a nuns' monastery, he forgot the young parrot when departing and went away. The novice nuns took it and cared for it. They gave it the name Buddharakkhita. Seeing it sitting in front of her one day, the senior nun said, "Buddharakkhita!" "What is it, noble lady?" "Do you have any mental engagement in development?" "I have none, noble lady." "Friend, one living in the presence of those who have gone forth ought not to be careless in one's personal bodily conduct; some mental engagement should be sought. But you will not be capable of anything else; make a recitation of 'bones, bones.'" Abiding by the senior nun's admonition, it went about reciting, "bones, bones."

One day, early in the morning, while it was sitting on top of an archway basking in the morning sun, a bird of prey seized it with its cage of talons. It made the sound "kiri kiri!" Hearing it, the novice nuns, saying, "Noble lady, Buddharakkhita has been seized by a bird! Let us free him!", took clods of earth and the like, chased it, and freed him. Bringing him and setting him before her, the senior nun asked: "Buddharakkhita, what were you thinking at the time you were seized by the bird?" "Noble lady, I did not think of anything else; [I thought:] 'Only a heap of bones is taking a heap of bones and going; in which place will it scatter [them]?' Thus, noble lady, I thought only of a heap of bones." "Well done, well done, Buddharakkhita! In the future, this will be a condition for your destruction of existence." Thus, even animals there were engaged in the attention to the foundations of mindfulness. Therefore, generating in them understanding of the foundations of mindfulness, the Blessed One delivered this discourse.

Here, "ekāyana" means a single path. For of path:

"Maggo, pantho, patho, pajjo, añjasaṃ, vaṭuma, ayanaṃ; / Nāvā, uttara-setu, kullo, and bhisi-saṅkamo [are synonyms of path]."

There are many names. Here, this [path] is spoken of by the name 'ayana' [way/going]; therefore, regarding 'this is the ekāyana path, monks', the meaning here should be understood as: this is a single path, monks, not one that is bifurcated into two paths. Or else, it is 'ekāyana' because it is to be gone on (ayitabba) by one alone (ekena). 'By one alone' means by one who has abandoned association with a group, who is secluded, with a solitary mind. 'It is to be gone on' means it is to be practiced; or 'ayana' means they go by it, meaning they go from saṃsāra to Nibbāna. 'Ekāyana' means the path of the One (ekassa ayano). 'Of the One' means of the foremost. And the Blessed One is the foremost among all beings; therefore, 'of the Blessed One' is what is meant. For although others also go by it, even so, it is the Blessed One's path alone because it was produced by him. As he said: 'For indeed, brahmin, the Blessed One is the producer of the unarisen path', and so forth. Or 'ayana' means it goes (ayati), meaning it proceeds, it operates. 'Ekāyana' means going in one (ekasmiṃ ayano), which means it operates only in this Dhamma and Vinaya, not anywhere else. As he said: 'Indeed, Subhadda, in this Dhamma and Vinaya the noble eightfold path is found.' This is only a distinction in teaching, but in meaning it is just one. Moreover, 'ekāyana' means it goes to one (ekaṃ ayati). What is meant is that although in the preliminary stage it proceeds in the mode of development with various aspects, in the subsequent stage it goes to Nibbāna alone. As Brahmā Sahampati said:

Seeing the end of birth, compassionate with welfare,
He knows the ekāyana path;
By this path they crossed over in the past,
They will cross over, and they cross over the flood.

Some, however, following the method of the verse 'They do not go to the beyond twice', say it is 'ekāyana' because it goes to Nibbāna once. That is not correct. For to express this meaning, the phrasing should be 'sakiṃ ayano' [going once]. But if the meaning were construed and stated as 'its going is one (ekaṃ ayanamassa), a single course and occurrence', the phrasing would be fitting, yet the meaning is not fitting either way. Why? Because here the preliminary path is intended. For the preliminary path of mindfulness meditation, operating on the four objects beginning with the body, is what is intended here, not the supramundane one; and that [preliminary path] goes many times, and its going is manifold.

And in the past, too, there was indeed a discussion among the great theras regarding this term. The thera Tipiṭaka Cūḷanāga said: 'It is the preliminary path of mindfulness meditation.' His teacher, however, the thera Tipiṭaka Cūḷasuma, said: 'It is the mixed path.' 'Is it the preliminary one, venerable sir?' 'It is the mixed one, friend.' But when the teacher kept speaking again and again, [Cūḷanāga] did not contradict him and remained silent. They arose without having resolved the question. Then the senior elder teacher, going to the bathhouse, reflected: 'I said it is the mixed path; Cūḷanāga employs the term taking it as the preliminary path. What indeed is the conclusion here?' Rehearsing the sutta from the beginning, at this passage—'For whoever, monks, should thus develop these four foundations of mindfulness for seven years'—he noticed: 'There is no such thing as a supramundane path having arisen and persisting for seven years. The mixed path spoken of by me is not admissible. Only the preliminary path seen by Cūḷanāga is admissible.' Having realized this, when the preaching of the Dhamma was proclaimed on the eighth day, he went.

The theras of old, they say, were lovers of hearing the Dhamma; as soon as they heard the sound, they assembled all at once, saying, 'I first! I first!' And on that day it was the turn of the thera Cūḷanāga. When he sat on the Dhamma seat, took the fan, and recited the preliminary verses, it occurred to the elder standing at the back of the seat: 'I will not speak having sat down in secret.' For the theras of old were free from envy. They did not go about upholding their own preference like a bundle of sugar cane; they accepted reason alone and rejected what was without reason. Therefore the elder said: 'Friend Cūḷanāga.' He, recognizing the voice as that of his teacher, set aside the Dhamma and said: 'What is it, venerable sir?' 'Friend Cūḷanāga, the mixed path spoken of by me is not admissible; only the preliminary path of mindfulness meditation spoken of by you is admissible.' The thera thought: 'Our teacher is master of all the scriptures, a Tipiṭaka expert, one who has awakened through learning; yet even for a monk of such a kind this question is perplexing. In the future, my brothers will be perplexed by this question. Taking a sutta, I will settle this question.' [And he cited] from the Paṭisambhidāmagga: 'The ekāyana path is called the preliminary path of mindfulness meditation.'

The eightfold is the best of paths, the four truths the best of truths;
Dispassion is the best of dhammas, and the Visionary the best of two-footed beings.

This is the path, there is no other, for the purification of vision;
Enter upon this [path]! It is the crushing of Māra's army;
Having entered upon this, you will make an end of suffering. —

Having cited this sutta, he presented it.

'Path': in what sense is it a path (magga)? In the sense of going to Nibbāna, and in the sense that it is to be sought out (magganīya) by those who seek Nibbāna. 'For the purification of beings': for the purpose of the purification of beings whose minds are defiled by stains such as lust and by corruptions such as covetousness and unrighteous greed. For indeed, by this very path—beginning with the Buddhas named Taṇhaṅkara, Medhaṅkara, Saraṇaṅkara, and Dīpaṅkara, who arose in a single kappa more than four incalculables and a hundred thousand kappas ago, and ending with the Sage of the Sakyas—countless fully awakened Buddhas, many hundreds of paccekabuddhas, and noble disciples beyond calculation: all these beings, having washed away the stain of the mind, reached ultimate purification. But there is no designation of defilement and cleansing with respect to the stain of form. For indeed:

'When form is defiled, mortals are defiled;
When form is cleansed, they are purified' — this was not stated by the Great Sage.

'When the mind is defiled, mortals are defiled;
When the mind is cleansed, they are purified' — so it was stated by the Great Sage.

As he said: “Through the defilement of the mind, monks, beings are defiled; through the cleansing of the mind, they are purified.” And that cleansing of the mind comes about through this path of the foundations of mindfulness. Therefore he said: “for the purification of beings.”

“For the overcoming of sorrow and lamentation” means for the transcending, for the abandoning, of sorrow and of lamentation. For this path, when developed, leads to the overcoming of sorrow as in the case of Santati the Chief Minister and others, and to the overcoming of lamentation as in the case of Paṭācārā and others. Therefore he said: “for the overcoming of sorrow and lamentation.” For although Santati the Chief Minister—

“Purify what was before; / let there be nothing behind you. / If you grasp nothing in between, / you will wander at peace.” (Sn 945)—

attained arahantship together with the analytical knowledges as soon as he heard this verse, and Paṭācārā—

“There are no children for protection, / nor a father nor even relatives; / for one overtaken by the Ender, / there is no protection among kin.” (Dhp 288)—

was established in the fruit of stream-entry upon hearing this verse; yet because there is no such thing as development [of the path] without touching upon some state among body, feelings, mind, and mind-objects, it should be understood that they too overcame sorrow and lamentation precisely by this path.

“For the passing away of pain and distress” means for the passing away, for the cessation, of these two: bodily pain and mental distress. For this path, when developed, leads to the passing away of pain as in the case of Tissa Thera and others, and to the passing away of distress as in the case of Sakka and others.

Here, this is the explanation of the meaning: In Sāvatthī, it is said, a householder's son named Tissa abandoned forty crores of wealth, went forth, and lived in a wilderness without a village. His younger brother’s wife sent five hundred bandits, saying, “Go, deprive him of life.” They went, surrounded the thera, and sat down. The thera said: “Why have you come, lay devotees?” “We will deprive you of life.” “Lay devotees, take a surety from me and grant me life for just this one night.” “Renunciant, who will be your surety in this place?” The thera took a large stone, broke both of his thighbones, and said: “Is the surety suitable, lay devotees?” They withdrew, lit a fire at the head of the walkway, and lay down. Suppressing the pain and reviewing his virtue, joy and gladness arose in the thera based on his completely pure virtue. Then, developing insight step by step, he carried out the renunciant’s practice throughout the three watches of the night, and at the rising of the dawn, having attained arahantship, he breathed forth this inspired utterance:

“Having broken both my feet, / I will convince you; / I am repelled, I am ashamed, / of dying with lust.

Having reflected thus, / I developed insight into things as they are; / upon the arrival of the rising dawn, / I attained arahantship.”

Thirty other monks as well, having taken a meditation subject in the presence of the Blessed One and entered upon the rains retreat in a wilderness dwelling, lived saying, “Venerables, renunciant practice is to be done throughout the three watches of the night; one should not come into one another’s presence.” While they were drowsing at the time of dawn after doing the renunciant practice, a tiger came and took them away, monk by monk. Not a single person uttered even a word, saying, “A tiger has seized me!” When five or ten monks had been devoured in this way, on the observance day they asked, “Venerables, where are the others?” and learning [what had happened], they lived saying, “Now, the one who is seized must say, ‘I have been seized!’” Then, in the same manner as before, the tiger seized a certain young monk. He said, “A tiger, venerable sirs!” The monks took walking sticks and torches and pursued it, thinking, “We will free him!” The tiger climbed up to an inaccessible cliff where the monks could not go, and began to devour the monk starting from his big toe. The others said, “Now, good man, there is nothing for us to do; the distinction of monks becomes evident in a place like this!” Lying right in the mouth of the tiger, suppressing that pain and developing insight, he became a stream-enterer when he was devoured up to the ankles, a once-returner when devoured up to the knees, a non-returner when devoured up to the navel, and before the flesh of the heart was devoured, he attained arahantship together with the analytical knowledges and breathed forth this inspired utterance:

“Virtuous, observant, / wise, well-concentrated, / following upon a moment of negligence, / with mind hemmed in by a tiger,

Seized in its cage-like jaws, / laid atop a rock; / let the tiger devour me at will, / both the bone and the sinew; / I will destroy the defilements, / I will touch liberation.”

Another thera as well, named Pītamalla Thera, in his lay life had won the banner in three kingdoms, arrived at the island of Tambapaṇṇi, had an audience with the king, and was favored by the king. One day, while passing by the door of a mat shop, he heard the “Not Yours” passage: “Monks, form is not yours; abandon it. When you have abandoned it, that will lead to your welfare and happiness for a long time.” He thought: “Form is indeed not one’s own, nor is feeling.” Making that very thought his goad, he left home, went to the Mahāvihāra, requested the going forth, received the going forth and the higher ordination, mastered the two matrices, took thirty monks, and went to the Gabalavāliya Compound to do the renunciant practice. When his feet failed him, he walked up and down on his knees. In the night, a deer hunter, thinking he was a deer, struck him. The spear passed completely through him. Having had that spear removed, he filled the wounds with grass bundles, seated himself on a flat rock, composed himself, developed insight, and attained arahantship together with the analytical knowledges. Having declared it to the monks who had come at the sound of his clearing of the throat, he breathed forth this inspired utterance:

"Spoken by the best of Buddhas, / speaker of the foremost in all worlds:
'This form is not yours; / you should abandon it, monks.

Impermanent indeed are conditioned things, / subject to rising and passing away;
Having arisen, they cease; / their calming is bliss.'"

Thus, first of all, this path leads to the cessation of suffering, as in the case of Thera Tissa and others.

Sakka, ruler of the gods, on the other hand, seeing his own fivefold warning sign, terrified by the fear of death and overcome with grief, approached the Blessed One and asked a question. At the end of the explanation of the question on equanimity, together with eighty thousand devas, he became established in the fruit of stream-entry. And his rebirth became once again natural and secure.

The devaputta Subrahmā too, surrounded by a thousand celestial nymphs, was experiencing heavenly splendor. There, five hundred celestial nymphs, plucking flowers from a tree, passed away and were reborn in hell. Wondering, "Why are they tarrying so long?", he reflected and recognized their rebirth in hell. Inquiring, "How much indeed is my remaining life?", he noticed the exhaustion of his own life span and saw that, having passed away, he would be reborn in that very same hell. Terrified and overcome with intense grief, thinking, "The Teacher will dispel this grief of mine, no one else," he took the remaining five hundred celestial nymphs, approached the Blessed One, and asked a question:

"Always terrified is this mind, / always agitated is this heart,
Regarding troubles that have not yet arisen, / and also regarding those that have befallen.
If there is what is free of terror, / tell that to me who ask." (SN 1.98)

Then the Blessed One said to him:

"Not other than by awakening and austerity, / not other than by restraint of the senses,
Not other than by the relinquishment of all, / do I see safety for living beings." (SN 1.98)

At the conclusion of the teaching, together with the five hundred celestial nymphs, having become established in the fruit of stream-entry, he made that splendor permanent and went right back to the deva world. Thus it should be understood that this path, when developed, leads to the cessation of grief, just as in the case of Sakka and others.

"For the attainment of the true method": the true method is called the noble eightfold path; it is said for its attainment, for its acquisition. For this mundane path of mindfulness, developed in the preliminary stage, leads to the attainment of the supramundane path. Therefore he said: "for the attainment of the true method." "For the realization of Nibbāna": it is said for the realization, for the personal experience, of the deathless, which has received the name 'Nibbāna' because it is free from the weaving thread of craving. For this path, when developed, accomplishes step by step the realization of Nibbāna. Therefore he said: "for the realization of Nibbāna."

In this context, although when "for the purification of beings" is said, the overcoming of sorrow and so forth are certainly accomplished in meaning, yet, except for those skilled in the methods of the Dispensation, they are not obvious to others; and the Blessed One does not first make people skilled in the methods of the Dispensation and only afterwards teach the Dhamma. Rather, he makes each respective meaning known by each respective discourse. Therefore, making clear and demonstrating each respective purpose that the direct path accomplishes, he said: "for the overcoming of sorrow and lamentation," and so forth. Or, because whatever purification of beings is brought about by the direct path occurs through the overcoming of sorrow and lamentation; the overcoming of sorrow and lamentation occurs through the cessation of suffering and grief; the cessation of suffering and grief occurs through the attainment of the true method; the attainment of the true method occurs for the realization of Nibbāna. Therefore, demonstrating this sequence as well, having said "for the purification of beings," he said "for the overcoming of sorrow and lamentation," and so forth.

Moreover, this is the praise of the direct path. For just as the Blessed One—[saying,] "Monks, I will teach you the Dhamma good in the beginning, good in the middle, good in the end, with the right meaning and phrasing; I will proclaim the spiritual life, utterly complete and purified, that is, the six sets of six" (MN 3.420)—spoke praise of the teaching on the six sets of six with eight phrases; and just as in the teaching on the noble lineages—[saying,] "Monks, there are these four noble lineages, primal, of long standing, traditional, ancient, unadulterated, formerly unadulterated, not being adulterated, which will not be adulterated, not disparaged by wise recluses and brahmins" (AN 4.28)—he spoke praise with nine phrases; so too, he spoke praise of this direct path with seven phrases beginning with "for the purification of beings." If it is asked why: in order to arouse enthusiasm in those monks. For having heard the utterance of praise, those monks, filled with enthusiasm—thinking, "This path, it is said, destroys the four perils consisting of sorrow, which is anguish of the heart; lamentation, which is verbal rambling; suffering, which is bodily disagreeableness; and grief, which is mental disagreeableness; and brings the three distinctions of purification, the true method, and Nibbāna"—will consider that this teaching of Dhamma is to be learned, mastered, remembered, and recited, and that this path is to be developed. Thus he spoke praise in order to arouse enthusiasm in those monks, like blanket merchants praising blankets and the like.

For just as when a merchant of blankets worth a hundred thousand proclaims, 'Take a blanket!', people do not yet know what sort of blanket it is—for even hair blankets, woolly hair blankets, and the like, which are foul-smelling and rough to the touch, are also called blankets; but when it is proclaimed by him, 'It is a red blanket from Gandhāra, delicate, radiant, and soft to the touch,' then those who are able buy it, and even those who are not able wish to see it—in the very same way, even when it was said, 'Monks, this is the direct path,' it was not yet evident what sort of path it is, for paths of various kinds that do not lead to release are also called 'paths.' But when it is said, 'for the purification of beings,' and so on, they will think, 'This path, it is said, destroys four perils and brings three distinctions; this Dhamma teaching is to be grasped, mastered, retained, and recited, and this path is to be developed.' Thus, speaking in praise, he said: 'for the purification of beings,' and so on. And just as with the simile of the merchant of blankets worth a hundred thousand, so also similes of merchants of red Jambunada gold, water-clearing gems, purest pearls, corals, and the like should be brought in here.

'Yadidaṃ' ('that is to say') is a particle; 'those which are these' is its meaning. 'Four' is a delimitation by number. By this, he demonstrates the limit of the establishments of mindfulness: not fewer than that, not more. 'Establishments of mindfulness' (satipaṭṭhāna): there are three establishments of mindfulness; it means the domain of mindfulness, it also means the Teacher's freedom from aversion and attraction toward disciples who practice in threefold ways, and it also means mindfulness itself. For in such passages as: 'Monks, I will teach the origination and the cessation of the four establishments of mindfulness; listen to that... And what, monks, is the origination of the body? Through the origination of nutriment is the origination of the body' (Saṃ. Ni. 5.408), the domain of mindfulness is called 'establishment of mindfulness.' Likewise in: 'The body is the presence (upaṭṭhāna), not mindfulness; but mindfulness is both the presence and mindfulness' (Paṭi. Ma. 3.35), and so on. Its meaning is: it establishes itself in this, thus it is a base (paṭṭhāna). What establishes itself? Mindfulness. The base for mindfulness is 'establishment of mindfulness' (satipaṭṭhāna); or, a principal place (padhānaṃ ṭhānaṃ) is a 'paṭṭhāna.' The base for mindfulness is an establishment of mindfulness, like an elephant station, a horse station, and so on.

In: 'There are three establishments of mindfulness which the noble one cultivates, cultivating which the Teacher is worthy to instruct a group' (Ma. Ni. 3.311), here the Teacher's freedom from aversion and attraction toward disciples practicing in threefold ways is called 'establishment of mindfulness.' Its meaning is: because it is to be established (paṭṭhapetabbato), it is an establishment (paṭṭhāna), meaning because it is to be set rolling. Established by what? By mindfulness. An establishment through mindfulness is 'satipaṭṭhāna.' But in such passages as: 'The four establishments of mindfulness, when developed and cultivated, fulfill the seven factors of awakening' (Ma. Ni. 3.147), mindfulness itself is called 'establishment of mindfulness.' Its meaning is: it establishes itself, thus it is an establishment; it stands present, descending into, leaping forward into, spreading out and operating, is the meaning. Mindfulness itself is an establishment of mindfulness. Alternatively, it is mindfulness in the sense of remembering, and an establishment in the sense of standing present. Thus it is mindfulness and it is an establishment, hence an 'establishment of mindfulness.' This is what is intended here.

If so, why is it plural as “foundations of mindfulness” (satipaṭṭhānā)? Because of the plurality of mindfulness. For these mindfulnesses are plural according to the difference of their object. Then why is it singular as “path” (maggo)? Because it is singular in the sense of being a path. For all four of these mindfulnesses attain oneness in the sense of being a path. For this has been said: “Path: in what sense is it a path? In the sense of going to Nibbāna, and in the sense of being sought by those who seek Nibbāna.” Furthermore, later on all four of these, accomplishing their task with respect to the objects such as the body, go to Nibbāna, and from the beginning they are sought by those who seek Nibbāna; therefore, all four are called one path. And this being so, the teaching is well-connected by way of verbal continuity, as in: “Bhikkhus, I will teach you the path that crushes the army of Māra; listen to it… And what, bhikkhus, is the path that crushes the army of Māra? That is to say, the seven factors of enlightenment” (SN 5.224), and so on. Just as “the crusher of the army of Māra” and “the seven factors of enlightenment” are one in meaning, and there is only a difference of phrasing here, so “the direct path” and “the four foundations of mindfulness” are one in meaning, and there is only a difference of phrasing here. Therefore, it is singular because of oneness in the sense of being a path, and it should be understood as plural because of the plurality of mindfulness through the difference of object.

Why, then, were precisely four foundations of mindfulness spoken of by the Blessed One, neither fewer nor more? Because of the benefit to those who are trainable. For among the trainable who are classified twofold according to whether they are dull or sharp—those with a temperament inclined to craving, those with a temperament inclined to views, those who make tranquility their vehicle, and those who make insight their vehicle—for a dull person of a craving temperament the coarse foundation of mindfulness of contemplation of the body is the path of purification; for a sharp person, the subtle foundation of mindfulness of contemplation of feeling. For a dull person of a view temperament, the foundation of mindfulness of contemplation of mind, which is not highly differentiated, is the path of purification; for a sharp person, the foundation of mindfulness of contemplation of dhammas, which is highly differentiated, is the path of purification. And for a dull person who makes tranquility their vehicle, the first foundation of mindfulness, whose sign is to be attained without difficulty, is the path of purification; for a sharp person, the second [foundation of mindfulness is], because they do not remain fixed on a coarse object. For a dull person who makes insight their vehicle, the third, whose object is not highly differentiated, [is the path of purification]; for a sharp person, the fourth, whose object is highly differentiated. Thus, precisely four were spoken of, neither fewer nor more.