What This Concept Is Saying
The grammar of the word 繫
The most counterintuitive thing about this term is the word 繫 (xì). In Buddhist Chinese, 繫 appears most often in phrases like 結繫 (knotted to) or 纏繫 (entangled in), and the reflex is to read 無色界繫 as "fettered to the formless realm." The *Abhidharmakośa* (《阿毘達磨俱舍論》, T1558) explicitly preempts this reading: it glosses 繫 as 繫屬 (xìshǔ) — "belonging-to" or "classified under." So 無色界繫 is a *classifier*, the way a librarian files a book under a category. The whole phrase says: "this dharma belongs to the formless realm." That is all.
That small translation move — 繫 → 繫屬 — is what unlocks the entire apparatus. Read 繫 as bondage, and you imagine a being imprisoned somewhere. Read it as classification, and you see a much more sober project: a complete inventory of which phenomena, on close analysis, fall into which of the three realms. Three such classifiers exist, in parallel:
- 欲界繫 (*kāmadhātu-saṃprayukta*) — belonging to the desire realm - 色界繫 (*rūpadhātu-saṃprayukta*) — belonging to the form realm - 無色界繫 (*ārūpyadhātu-saṃprayukta*) — belonging to the formless realm
Together, these three tags classify every conditioned dharma — every phenomenon that arises and ceases under conditions.
What the formless realm actually is
The name itself is a small grammatical contraction. The full form, the *Kośa* notes, is 無色所屬界 — "the realm that is the belonging-domain of no-form" — and the middle words are dropped. In that contraction, 色 (*rūpa*) is taken in its sense of 變礙 (transformation-and-resistance — matter that has physical impact) or 示現 (manifestation). The formless realm is therefore not "a realm that has invisible things in it." It is "the realm characterized by the absence of such material phenomena." The *Kośa* is explicit on a subtle point that matters: the formless realm's body is not rūpa, but it is *also not* a positive entity called "the absence of rūpa." There is no such second thing. There is only the realm whose defining mark is that rūpa does not obtain there.
What populates that realm are the four 無色定 (formless attainments), four samādhis (absorptions) that go beyond even the form-realm absorptions:
1. 空無邊處 (*ākāśānantyāyatana*) — the station of infinite space: the mind takes boundless space as its object. 2. 識無邊處 (*vijñānānantyāyatana*) — the station of infinite consciousness: the mind takes consciousness itself, with no further object, as its object. 3. 無所有處 (*ākiñcanyāyatana*) — the station of nothingness: the mind takes "nothing whatsoever" as its object. 4. 非想非非想處 (*naivasaṃjñānāsaṃjñāyatana*) — the station of neither-perception-nor-non-perception: the subtlest state, where perception is so refined it cannot be said either to be present or absent.
The *Yogācārabhūmi* (《瑜伽師地論》, T1579) handles the four under its 七界 (seven-realm) schema: 光明界, 清淨界, 空處界, 識處界, 無所有處界, 非想非非想處界, 滅界. Of these seven, "由無色界攝四無色" — the formless realm encompasses the four formless stations (空處, 識處, 無所有處, 非想非非想處). 滅界, the station of cessation, is left outside; it is a different category. The *Yogācāra* notes that 非想非非想處 is entered "由無相作意方便趣入, 想極細故, 取為第一" — through the device of signless application of mind; because its perception is exceedingly subtle, it is reckoned the highest.
That is the territory the tag 無色界繫 marks. The classical treatises then lay down several quite specific criteria for which dhammas receive the tag.
Criterion 1: The eighteen dhātus (十八界) — only the last three
The cleanest criterion appears in the eighteen-dhātu analysis. Among the eighteen dhātus — six sense faculties, six sense objects, six sense consciousnesses — only the last three belong to the formless realm: 意界 (the mental faculty), 法界 (mental objects / dharmas), and 意識界 (mental consciousness). The terse verse from the *Kośa* says it all: 「無色繫後三」 — "bound to the formless: the last three."
Why only the last three? Because whoever is born in that realm has first let go of desire for material form (離色欲). Without that desire, the conditions for the 十色界 — the five sense organs and their five objects — are not assembled. And because in the formless realm there is no sense-organ (*所依*) and no sense-object (*所緣*) of the physical kind, the five sense-consciousnesses (眼識, 耳識, 鼻識, 舌識, 身識) cannot arise. What remains is the trio *manas* / *dharmas* / *manovijñāna* — mind operating on its own, with dharmas as object. This is the central image: in the formless realm, the apparatus of seeing, hearing, smelling, tasting, and touching is *entirely absent*. Only the mental apparatus is running.
Criterion 2: The twenty-two roots (二十二根) — only eight
When the same lens is turned on the twenty-two faculties (*indriya*), the *Kośa* applies the same principle with the shorthand 「無色如前」 — "in the formless, as before." Starting from the form-realm list, it removes:
- the three unconditioned roots (三無漏根: 未知當知根, 已知根, 具知根), - the female and male roots (女根, 男根), - the root of sorrow and the root of suffering (憂根, 苦根), - the five physical-sense roots (眼根, 耳根, 鼻根, 舌根, 身根), - the roots of joy and bliss (喜根, 樂根).
What is left, and therefore belongs to the formless realm, are eight: 意根, 命根, 捨根, and the five faith-roots (信等五根: 信, 進, 念, 定, 慧). The list preserves exactly what a formless-realm apparatus can still support: a faculty of mind, the life-faculty that anchors continuity, the neutral feeling-tone (捨 — neither joy nor suffering), and the five trained spiritual faculties that purify mind. What is *not* present is equally instructive: joy, bliss, sorrow, and suffering have all dropped out. The affective range has narrowed to neutral.
Criterion 3: The 三時現行 (Three-Times-Arising) framework — *when* is a dharma formless-realm-belonging?
The *Yogācārabhūmi* gives a more dynamic definition than the *Kośa*'s inventory. Instead of asking *what* is tagged, it asks *when* a formless-realm-belonging dharma is actually in operation. The text says:
「已得無色界繫對治, 若入彼定; 或復生彼, 未得上對治; 或得已出, 三時現行義。一切一分是無色界繫。」
A dharma counts as formless-realm-belonging when, in any of three time-slices, it is in operation:
1. 已得對治 + 入定: You have already obtained the countermeasure (the higher path that abandons the formless-realm fetters), and you have *entered* the formless attainment. 2. 生彼 + 未得上對治: You are *born* in the formless realm, and have not yet obtained the higher countermeasure. 3. 得已出: You have obtained the countermeasure and have already emerged.
In all three cases, the dharma is presently in operation, and a *part* (一分) of it is formless-realm-belonging. The *Yogācāra* then adds the blanket formula 「如色界繫法, 如是無色界繫法, 隨其所應, 當知亦爾」 — "as with form-realm-belonging dhammas, so with formless-realm-belonging dhammas: the rest should be known by analogy."
The framework tells us something important: the tag is not about *where a dharma lives* but about *when it is operating*. It can be operating while one is in the attainment, while one is reborn in that realm without having ascended past it, or while one has emerged from it after obtaining the countermeasure. The *same dharma* can be classified differently at different times.
Criterion 4: Causes within the formless realm (心法與修所成法之同類因)
The *Kośa* adds a fine-grained point about causation inside the formless realm. Among formless-realm-belonging dhammas, the 修所成 (cultivation-completion) ones take only *self-realm cultivation-completion* dhammas as their 同類因 (cause-of-same-type — the cause that produces another instance of the same kind of dharma). They do not take 聞所成 (learning-completion) dhammas or 思所成 (thinking-completion) dhammas as such a cause. The reason in the first case is simple: there is no formless-realm corresponding learning-completion dharma at all. The reason in the second case is the comparative weakness of thinking-completion: a lesser dharma cannot be the 同類因 of a greater one.
These causes are then further stratified into 九品 (nine grades). Within those nine, a lower grade cannot be the 同類因 of a higher one. So within the formless realm, the only thing that reliably produces more formless-realm-belonging dharmas is more of itself, at the same or higher grade.
Criterion 5: Heart-to-heart continuity (心無間生)
A whole section of the *Kośa* tracks how one *心* (heart-mind / citta) gives rise, without interval, to the next. The picture for the formless realm is:
- A formless-realm virtuous mind can arise, without interval, from nine hearts — the three formless-realm virtuous minds themselves, the form-realm virtuous minds, and the learner and non-learner (學, 無學) minds. - A formless-realm 有覆 (covered / obscured) mind can arise from seven hearts and can give rise to seven. - A formless-realm 無覆無記 (uncovered / indeterminate) mind arises only from the three formless-realm minds themselves, and gives rise to those three plus defiled minds of the desire and form realms.
This pattern is a complete picture of how a formless-realm heart enters samādhi, transitions between the four stations, exits into the path of learning, or falls back into defilement. It is also a precise picture of how a meditator's stream of attention actually behaves when it touches these states.
Criterion 6: How a formless-realm being continues (心等相續)
The *Kośa* records a doctrinal debate about how a formless-realm being maintains continuity at all, given that there is no body. The 對法諸師 (Abhidharma-traditional commentators) say continuity is maintained by 眾同分 (generic identity — the fact that a being of this kind persists as this kind) and 命根 (the life-faculty), both of which arise from the powerful samādhi and are said to "suppress form-perception" (能伏色想); their force is comparatively strong. The 經部 (Sautrāntika) teachers say mind and mental factors (心所) support each other and no separate support needs to be posited.
What both sides share is the underlying premise: in the formless realm, mind does not depend on matter. They only disagree about what, in the absence of matter, does the work that matter would otherwise do.
Criterion 7: The narrowness of attention (意近行之界繫)
The *Kośa* also analyses 意近行 (*manasikāra* — "the approach of mind," a kind of mental attention) and finds another clean cut. In the 空無邊處近分 (the near-attainment of infinite space — the preparatory stage before the full attainment), the four kinds of 意近行 grounded in 捨 can take 色, 聲, 觸, 法 (color, sound, touch, dharmas) as their object. But when the object *is* the formless realm itself, only the 法意近行 (dharma-mindfulness) is in play. The four full formless attainments and the three upper near-attainments likewise use only the 法意近行.
Two further constraints are folded in. The four full formless attainments (根本地) do not cognize their lower stations (不緣下地). The three upper near-attainments do not cognize material form at all (不緣色). Each station sees only what its own apparatus can see.
Criterion 8: Birth without intermediate existence (徙生)
The *Yogācāra* adds one more item that captures the formless-realm-born being's mode of arrival: 「於有色處, 依止中有而有去來; 於無色處, 唯有徙生。」 — "In places with form, going and coming rely on an intermediate existence (中有); in the formless place, there is only transferred birth (徙生)."
A being reborn in a form-realm or desire-realm passes through a 中有 — an interim "in-between" existence that travels from the old life to the new. A formless-realm being has no such interim vehicle. Its next existence simply *shifts over* (徙), without a body to inhabit during the transition. The theoretical reason is consistent with the rest of the apparatus: there is no body in the formless realm, so there is no body for a 中有 to ride in.
The crossings: aggregates, supports, defilements, and realizations
Finally, 無色界繫 appears in several other contexts, mostly to clarify that the same category can wear multiple hats at once. The *Yogācāra* notes that the 五蘊 (five aggregates) can overlap with all three realms and 不繫 (the unconditioned) at once, with the criterion being 「為義」 — what the aggregate *is functioning as* in a given situation, not its abstract identity. The same 受蘊 (feeling-aggregate) can be desire-bound in one configuration and formless-bound in another.
On defilements (隨眠), the text answers 「三染. 餘通二種」 — three are defiled, the rest are of two kinds — and on the supports cut off at the 不還果 (once-returner's fruit), 「欲界一切, 色無色界不定」 — in the desire realm all [supports are cut], in the form and formless realms it is not fixed. On the 六現觀 (six direct-realizations), the *Yogācāra* distributes them as: one only in the desire realm; one (or a part of one) either desire-, form-, or formless-bound; four in the unconditioned; one that crosses both bound and unbound. So 无色界繫 is not a sealed compartment.
Where this sits in the path of liberation
To situate the concept in the larger arc: 無色界繫 is an *analytical* tool, not a *liberating* one. It belongs to the *abhidharma* arm of the tradition — the systematic classification of phenomena. Its role is upstream of liberation in the sense that it sharpens perception: it teaches the practitioner to see phenomena as filed-under-categories, to recognize that categories shift with operation, and to know exactly what equipment remains when sensory support is removed. Downstream, that sharpened seeing becomes fuel for the path of seeing (見道) and the path of cultivation (修道). The *Yogācāra*'s observation that the same aggregate can be desire-bound, form-bound, formless-bound, *and* unbound is a hinge-point toward the later Mahāyāna insight that all dhammas are empty of fixed nature — the analytical apparatus, taken seriously, leans in that direction. So 無色界繫 sits neither at the start nor at the end of the path; it sits in the middle, as a *clarifying lens* through which the path becomes more visible.
Walking Through This in Contemporary Life
The classical material here is highly technical, and honest mapping requires flagging where the contemporary analogues break down. Let's walk through each criterion and see what it looks like in familiar experience.
What it means, experientially, that only the last three of the eighteen dhātus are running. In the formless realm, there is no image, no sound, no smell, no taste, no bodily sensation as object. The closest contemporary analogue is not a place but a *state*: a moment when sensory input has effectively gone silent and only mental activity continues. Think of the moment when you close your eyes in a quiet room, drop the body's signals, and follow a thought into a place with no edges. Anyone who has meditated, or been absorbed in thought, or fallen half-asleep into a state where sensory input is muted, knows a relative version of this. The classical picture is more absolute than that — but the relative version is the entry door.
Where the mapping goes wrong is when we treat the formless realm as "a state you've experienced once and so you've been there." The classical picture is not a flash but an established continuity; the texts speak of beings *born* there. The point of the inventory is not "you've visited" but "if such a state were continuous, here is exactly which dhātus would still be operating." The *abhidharma* mind is not asking for a tourist visa; it is asking what would be left standing.
What the eight remaining roots look like in experience. A faculty of mind (意根), the continuity-of-being (命根), a feeling-tone that is neither pleasant nor unpleasant (捨), and five trained capacities of trust, effort, memory, samādhi, and insight. What is *absent* — joy, bliss, sorrow, suffering — is striking. The closer contemporary analogue is the kind of deep equanimity where strong affect has receded from the foreground and only steady attention remains. Anyone who has sat for a long retreat and felt the bright highs and dark lows of early sessions quiet into a steady middle knows this subtraction. The classical texts are explicit that in the formless realm the affective range has *narrowed to neutral*, and that narrowing is part of what makes the attainment possible.
What the 三時現行 framework looks like in practice. Three different relationships to the same formless-realm-belonging dharma:
1. 已得對治 + 入定 looks like a practitioner who has realized that a subtle attachment is past — and yet *re-enters* the state where it used to grip, in order to see it through to the end. You have the countermeasure in hand; you return to the old ground to clean up.
2. 生彼 + 未得上對治 looks like a meditator who has stabilized in a formless attainment but has not yet penetrated further. Fully inside the state; the higher path not yet reached.
3. 得已出 looks like someone who has come out the other side, still carrying some traces, with the countermeasure fully in hand.
Modern practitioners tend to want a single dramatic breakthrough. The classical framework insists that mastery is a *series* of time-slices, each requiring its own work, and the same dharma is "formless-bound" at three different points of one's relationship to it.
What 徙生 without 中有 looks like. This is the strongest claim of all and the hardest to map. The classical picture says that for a being reborn without a body, the transition is *without vehicle* — the mind is the only thing that moves. There is no interim body for a 中有 to ride. We don't have a clean contemporary analogue for this; the closest we can say is that the classical theory *refuses to interpolate* a physical vehicle for a being without one. It treats the continuity as genuinely mind-only. The instruction for the contemporary reader is less "imagine this" than "notice how the theory refuses to imagine anything else."
The 意近行 rules map more cleanly. They tell us that when you are *preparing* for the infinite-space station (空無邊處近分), your mind's attention can still take color, sound, touch, or dharmas as object — it is still partly sensory. But once you are *in* the full attainment, or in the three upper near-attainments, only dharmas are objects. And once you are in a full formless attainment, you cannot perceive the lower stations. This is a precise instruction about the *narrowing of attention*. Anyone who has practiced single-pointed meditation knows the experience of attention progressively excluding lower objects — first the body drops out, then sounds, then images, then named things, until only a refined mental object remains. The 意近行 rules are a formal map of that progression.
The single most important mapping error to flag: 無色界 is *not* 「空」 in the Mahāyāna sense of emptiness (空性). The first formless attainment is 空無邊處 — "infinite space" — which is a *positive object of meditation* (boundless space), not the philosophical emptiness of self-nature. Conflating these two empties is one of the easiest contemporary errors and produces a great deal of confusion in popular writing.
A second mapping error: 無色界 is not 「天堂」 in the popular sense, nor 「極樂」 or any other paradise. It is a *classification of dhammas*, not a destination ranked by moral goodness. A formless-realm being may have been reborn there through deep samādhi, but the text repeatedly reminds us that these are still *bound* (繫) — there are still fetters; they are just subtler ones. The same logic that places some dhammas in the desire realm places other dhammas in the formless realm; neither is "where the good people go."
A third error: 無色界 is not a metaphor for death or non-existence. It is a positive classification of dhammas, including very specific ones: 意, 法, 意識, 意根, 命根, 捨根, 信等五根, and the four samāpattis. None of those is "nothing."
Why a Contemporary Practitioner Needs This Concept
If you are not a specialist in *abhidharma*, this concept can look like a dusty taxonomic curiosity. The reasons it still matters — and the reasons the classical masters put serious effort into it — are practical rather than archival.
First, it is training in analytical precision. To read 無色界繫 carefully is to practice seeing every conditioned phenomenon as *belonging somewhere* — and to notice that the "somewhere" is not a place but a category, and that the category shifts depending on when the phenomenon is operating. That kind of attention — present, technical, and yet dynamic — is exactly the attention that the rest of the path asks of a practitioner. A reader trained by this apparatus is less likely to mistake a passing state for a permanent attainment, less likely to believe that spiritual categories carve fixed objects in the world.
**Second, it is the cleanest specification we have of what *mind-only* means.** The whole apparatus is a careful answer to the question: "If matter is removed, what is left?" And the answer is: a faculty of mind (意根), a life-faculty (命根), neutral feeling (捨), trained spiritual capacities (信等五根), and four specific attainments. The classical taxonomists were not indulging in metaphysics; they were mapping the actual equipment of mind when sensory support is gone. For a contemporary meditator, knowing this map is part of knowing what one is doing when one pursues a samādhi that goes beyond form.
Third, the 三時現行 framework teaches a kind of patience. It says: a dharma is formless-realm-belonging when you are inside it, when you are reborn in it, and when you have emerged from it. In other words, mastery is not a single moment. Each time-slice requires its own relationship to the dharma. This is a quiet corrective to a contemporary culture that fetishizes peak experiences.
Fourth, the twenty-two-roots map tells a precise story about which capacities remain and which drop out. Joy, bliss, sorrow, and suffering are absent. The five spiritual faculties are present. That precise subtraction is a map of what a meditator can expect when refining attention to that degree: deep equanimity, but also the loss of strong affect — both facts that a contemporary practitioner needs to know *before* entering such a state.
**Fifth, the seven-realm schema in the *Yogācāra* — 光, 淨, 空處, 識處, 無所有處, 非想非非想處, 滅 — is one of the most striking ontological maps in the Buddhist tradition.** It places four stations under the formless realm's umbrella and leaves 滅界 outside it. To read this map is to realize that the Buddhist analysis of mind distinguishes between very fine shades of refinement and refuses to collapse them. That kind of distinction is, in itself, a quiet liberation from the modern habit of blurring mental states into a generic "meditative experience."
**Sixth, the cross-cutting observation that the five aggregates can simultaneously be desire-bound, form-bound, formless-bound, *and* unbound is a strong philosophical statement.** It tells you that the categories do not carve reality at its joints in any absolute way; they carve *aspects of operation*. This is one of the technical roots of the later Mahāyāna insight that all dhammas are empty of fixed nature. The *abhidharmic* apparatus, taken seriously, leans toward that insight. A contemporary reader who reaches the Mahāyāna texts without first encountering this apparatus often arrives at emptiness *philosophically* without having first *seen* the multiplicity that emptiness is meant to dissolve. The apparatus is, in a sense, the prior training the emptiness teachings presuppose.
Seventh, the absence of 中有 in formless-realm birth is a reminder that Buddhist cosmology is not a uniform picture. Different modes of birth belong to different modes of being. A model that respects those differences is more useful than one that flattens them. There is an analogue in contemporary cognitive science — the reminder that brain-state and mind-state do not always align cleanly, that different conditions of consciousness come with different boundary conditions — but the analogy is illustrative only. We cannot claim the classical taxonomy is *proven* by such parallels; we can only say the parallels suggest that *layered accounts of consciousness* are not unreasonable.
Common Misreadings and Clarifications
Misreading 1: 「繫 means bondage, so 無色界繫 means being fettered by the formless realm.」 The *Kośa* explicitly glosses 繫 as 繫屬 (belonging-to). The classifier is a tag, not a shackle. If a dharma is tagged 無色界繫, that means it is filed under the formless-realm column — not that it is imprisoned there.
Misreading 2: 「The formless realm is invisible or spiritual.」 The "formless" in the name refers to *rūpa* in its technical sense — material phenomena with resistance and manifestation — not to invisibility. A "formless-realm being" is not a ghost or a translucent being. The *Kośa* is careful: the formless realm's body is not rūpa, but it is *also not* a positive entity called "the absence of rūpa." The realm is characterized by the *non-obtaining* of rūpa, not by some positive form-of-non-rūpa.
Misreading 3: 「Formless realm = emptiness (空).」 The first formless attainment is 空無邊處 (*ākāśānantyāyatana*) — "infinite space." This is a *positive meditative object*, not the emptiness of self-nature (空性). Mixing these two empties is one of the easiest errors a contemporary reader can make. The first emptiness is a thing one fixes the mind *on*; the second emptiness is a thing one sees *through*.
Misreading 4: 「The formless realm is the highest or best realm.」 The texts do not rank the realms this way. They *classify* them. Formless-realm beings are still bound; the *Kośa* and *Yogācāra* both remind us that the fetters there are simply subtler. A formless-realm attainment can be a high accomplishment; it is not final liberation. The *Yogācāra* is explicit that even the 非想非非想處 is entered "由無相作意方便趣入" — by a device, not by final insight.
Misreading 5: 「Formless-realm dhammas are different in kind from desire-realm dhammas.」 Not so. The *Yogācāra*'s 五蘊 + 界繫 cross-tabulation shows the *same aggregate* (色, 受, 想, 行, 識) can be tagged with different realm-classifications at different times. The same 受蘊 can be desire-bound, form-bound, formless-bound, *or* unbound. The classifier is about *operation*, not about metaphysical type. The traditional analysis is built to *resist* the temptation to reify the categories.
Misreading 6: 「A formless-realm being has no consciousness at all.」 The reverse is true. The *Kośa*'s inventory says exactly what is *still present* in the formless realm: 意, 法, 意識. That is the trio of mental faculty, mental object, and mental consciousness. The being *has* consciousness, and has it as its primary mode of being — not as a degraded version of itself. The formless realm is mind's own territory, not mind's absence.
Misreading 7: 「A formless-realm being must once have been human.」 The classical texts do not require this. What is required is the practice of deep formless samādhi, which can be entered from any human birth where the conditions are present. The texts speak of being *born* (生彼) in the formless realm, not of human rebirth as such.
Misreading 8: 「The 中有 (intermediate existence) is universal in Buddhist cosmology.」 The *Yogācāra* explicitly limits 中有 to places "with form." Formless-realm beings have only 徙生 (transferred birth). There is no single rule for all rebirths; the rules differ by mode of being.
Misreading 9: 「無色界 is a synonym for 涅槃.」 It is not. 無色界 is still part of *saṃsāra* in the broad sense. 涅槃 is 不繫 (unbound). The *Yogācāra* even includes 滅界 separately from the formless realm's four stations, precisely to mark its distinctness from the deepest formless attainment. The line between "very refined conditioned mind" and "the unconditioned" is exactly the line that this entire apparatus is built to keep visible.
Misreading 10: 「The four formless attainments are arranged from worst to best morally.」 The arrangement is *technical*, not moral. The non-learner who has entered 非想非非想處 is still subject to fetters — which is why the fetters of the formless realm are an explicit category in the classical literature, with their own stages of abandonment along the path. Refinement of object is not the same as liberation.
Misreading 11: 「The formless realm is irrelevant unless one is born there.」 The 三時現行 framework insists otherwise. A dharma is formless-realm-belonging not only when one is *in* the attainment but also when one has the countermeasure and enters, and when one has emerged. In other words, the same dharma functions in your practice whether or not you are currently "in" a formless station. The classical classification is built around *function*, not around where you happen to be sitting.
A note on the canonical sources
The detailed analytical work on 無色界繫 comes primarily from the two treatises excerpted here: the *Abhidharmakośa* (《阿毘達磨俱舍論》, attributed to Vasubandhu / 世親, T1558) and the *Yogācārabhūmi* (《瑜伽師地論》, T1579). The four formless attainments themselves appear in many earlier sūtras — for instance, in the *Saṃyuktāgama*'s exposition of the four *dhyānas* and four *ārupyas* — but the technical apparatus of *界繫* classification, *三時現行*, and the cross-tabulation with *五蘊*, *六現觀*, and *二十二根* is the work of systematic *abhidharma* and *yogācāra* analysis, not of sūtra quotation. A contemporary reader should know that when the sources say 無色界繫, they are speaking the analytical language of these treatises, not paraphrasing a sūtra. To treat the analytical apparatus as if it were a direct quotation of the Buddha is a category error; to dismiss it as "later commentary" is to lose the practical precision it offers. Both errors are common. The honest middle is: the four formless attainments are early and sūtra-grounded; the classification system that tags them with 界繫 is later and analytical; the two work together in the classical tradition, and the analysis is meant to *clarify* what the attainments actually are.