Web search is unavailable, but the provided classical materials are extensive and well-sourced. I'll write the interpretation based on these.

定共戒 (Samādhi-saṃvara): The Precept That Breathes with Your Stillness

What This Concept Is Actually Saying

Most people encounter Buddhist precepts (戒, śīla) as rules: don't kill, don't steal, don't lie. You take them in a ceremony, you try to keep them, and when you fail, you feel guilty. 定共戒 (dìng-gòng-jiè, Sanskrit: *samādhi-saṃvara*) shatters this picture entirely. It is not a rule you receive. It is a purity that *happens to you* when the mind goes genuinely still.

The classical definition is precise: "非作法，是得法，得法時乃發斯戒" — "It is not something enacted through ceremony; it is something attained. When the attainment occurs, this precept arises of itself" (T1716). The word 共 ("together with") in the name does all the work: this precept is *born together with* samādhi (禪定, meditative absorption). You don't decide to keep it. You enter deep concentration, and the precept is already there, like warmth already there in fire.

What it does, mechanically. The texts say it "滅惡覺觀" — "extinguishes evil vitarka and vicāra" (T1716). 覺觀 (jué-guān) are the mind's initial and sustained discursive movements: the first flash of a harmful impulse and the lingering rumination that follows. In ordinary life, you might not act on a cruel thought, but the thought still churns. 定共戒 cuts at a deeper level than behavior — it stills the *impulse itself*. T1911 puts it vividly: "雖持律儀，念破戒事，名之為雜；定共持心，欲念不起，故名不雜" — "Even while keeping the formal precepts, if the mind entertains thoughts of breaking them, that is called 'mixed.' When samādhi-shared precept holds the mind so that desire does not arise — that is called 'unmixed.'"

So the architecture has three layers:

1. The ground: śīla as prerequisite. "尸羅不清淨，三昧不現前" — "If moral conduct (śīla) is not pure, samādhi will not manifest" (T1716). You cannot skip the behavioral foundation. The texts distinguish two levels of obstruction that pure śīla removes: 事障 (shì-zhàng, "event-obstructions" — gross behavioral disruptions) and 性障 (xìng-zhàng, "nature-obstructions" — the deep temperamental afflictions). Clearing event-obstructions yields access to 未來禪 (the "future" or preparatory concentration); clearing nature-obstructions yields 根本禪 (fundamental dhyāna). 定共戒 arises at both levels, but its depth tracks the depth of the samādhi it rides on.

2. The arising: simultaneous with the concentrated mind. T1558 (the *Abhidharmakośa*, 俱舍論) uses the term 靜慮律儀 (jìnglǜ lǜyí, "dhyāna-discipline") and states: "由得有漏根本近分靜慮地心，爾時便得，與心俱故" — "When one attains the mind of the fundamental or preparatory dhyāna ground (whether still with outflows), at that very moment one obtains this discipline, because it is *together with the mind*" (T1558). This is the critical phrase: 與心俱 (yǔ xīn jù) — "co-arising with consciousness." Unlike the prātimokṣa precept (別解脫戒, bié-jiětuō-jiè), which is generated by external instruction and ceremony (由他教力發), 定共戒 has no author. It is a structural property of a concentrated mind, the way roundness is a structural property of a sphere.

3. The scope: it governs mind, not just body and speech. Formal precepts (律儀戒) regulate what you *do* and *say*. 定共戒 regulates what you *are* in the moment of absorption. T1911: "定法持心，心不妄動，身口亦寂，三業皎鏡" — "The dhyāna-dharma holds the mind; the mind does not stir falsely; body and speech are thereby silent; all three karmas become a clear mirror." Body and speech go quiet *because* the mind has gone quiet — not the other way around.

Its position in the hierarchy. T1911 places it on a ladder of ten precepts: above 律儀戒 (formal discipline, which even a scattered ordinary person can keep) but below 隨道戒 (the precept that accompanies the path of a stream-enterer), 無著戒 (the non-attachment precept of a non-returner), 智讚自在戒 (the wisdom-praised sovereign precept of a bodhisattva), and 隨定具足戒 (the complete precept that follows the great samādhi of a fully matured practitioner). And crucially: "凡夫入定則能持得也" — "An ordinary person, upon entering samādhi, can hold this precept" (T1911). You do not need to be a saint. You need to be still.

Its fragility — and its honesty. Here is where 定共戒 differs most sharply from 道共戒 (dào-gòng-jiè, "path-shared precept"). T1911: "道共戒依道，道無失故戒亦無失；定共戒依定，定可退故戒有謝義" — "The path-shared precept depends on the path; since the path is never lost, the precept is never lost. The samādhi-shared precept depends on samādhi; since samādhi can regress, the precept can wither." This is not a flaw in the concept — it is the concept's radical honesty. It says: the purity you find in stillness is real, but it is *conditioned*. It depends on a state you can lose. The texts even preserve a debate about whether 定共戒 survives after you leave meditation: "有人言：入定時有，出定時無" (some say it exists only during absorption); "有人言：無作依定，定在不失，定退即謝也" (others say its unconditioned precept-body, 無作, persists as long as the samādhi-attainment has not fully decayed) (T1911). The tradition refuses to resolve the debate for you. The ambiguity is the teaching: *don't mistake a state for a realization.*

Its taxonomic home. T1558 opens with the famous verse: "律儀別解脫，靜慮及道生" — "Discipline is threefold: prātimokṣa (liberation-through-rules), dhyāna-born, and path-born" (T1558). 定共戒 is the "dhyāna-born" (靜慮生) member of this triad. It is further characterized as 隨心轉 (suí xīn zhuǎn) — "turning together with the mind" — meaning it persists even through changes of mental state and even in mindless (無心) absorption, unlike prātimokṣa which depends on conscious intention to maintain. And it belongs to the category of 斷律儀 (duàn lǜyí, "severing discipline") in its unconfined aspect: it doesn't merely *prevent* transgression; it *severs* the desire-realm afflictions that would produce transgression (T1558).

T1716 adds a doctrinal classification: 定共戒 belongs to the 三藏 (Tripiṭaka) teaching and is called 麁 (cū, "coarse" or "foundational") relative to the 圓教 (Perfect Teaching) precepts. This is not a dismissal — it is a placement. In the architecture of the path, 定共戒 is the indispensable middle story: above mere rule-following, below the irreversible purity of awakening. "豈非待前諸戒皆麁，唯圓為妙也" — "Are not all the preceding precepts 'coarse,' with only the Perfect being 'subtle'?" (T1716). Yes — but you cannot reach the roof without the middle floor.

One more structural point: the 四運心 (sì yùn xīn, "four phases of mental movement") practice. T1911 describes a contemplative method: in any encounter with the six sense-fields, you observe four phases — 未見 (not yet perceiving), 欲見 (wanting to perceive), 見 (perceiving), 見已 (having perceived). You investigate: where is the mind that arises? You cannot find it. "不為四運所亂，即持定共戒也" — "Not being thrown into disorder by the four phases: this is keeping the samādhi-shared precept" (T1911). This is not suppression. It is *seeing through* the impulse so completely that it has no purchase. The precept keeps itself because there is no one left to break it.

A Walk-Through in Everyday Life

Let's take a Tuesday evening. You've been at work for ten hours. Your partner says something mildly critical — "You forgot to call the plumber again" — and you feel the heat rise.

The prātimokṣa layer (律儀戒). You don't yell. You bite your tongue. You remember: I took a precept against harsh speech. So you say nothing, or you say something measured. But inside, the monologue is vicious. You are *holding the precept* while *thinking about breaking it*. T1911 calls this 雜 — "mixed." The behavior is clean; the mind is dirty.

Now imagine the 定共戒 layer. This is not something you "do" in the moment of irritation. It is the fruit of a different relationship to mind that you've built through sustained concentration practice. Suppose you have a daily sitting practice where you've developed genuine access concentration (近分定, the "neighborhood" of absorption). In that practice, you've learned what it feels like for the mind to *not grab*. Not to suppress the grab, but for the grab to simply not initiate, because the mind is too settled, too full of its own quiet, to lunge.

Now back to Tuesday. The criticism lands. But something is different. There is a half-second where, in an earlier year, the whole story would have ignited — *she always does this, she doesn't respect my time, I'll show her* — and the story would have dragged your speech and body along with it. Tonight, the spark lands on wet ground. The mind has a habit of *not lunging*, built not by willpower but by the structural change that repeated samādhi has wrought. You feel the sensation of heat, you feel the contraction in the chest, but the *discursive elaboration* — the 覺觀, the vitarka-vicāra — doesn't chain. You respond. Maybe you even say, "You're right, I'll do it tomorrow," and mean it. Not because you're a better person. Because the mind that would have fabricated the fight was *not present* in the way it used to be.

T1911's phrase "定法持心，心不妄動，身口亦寂" maps exactly: the dhyāna-quality holds the mind → the mind does not fabricate → body and speech go quiet as a *consequence*, not as a suppression.

Where people map this wrong. The most common error: thinking 定共戒 means "being calm under pressure" in the self-help sense. It does not. Self-help calm is still *you managing you*. There is an agent gripping the steering wheel, white-knuckling. 定共戒 is what happens when the grip loosens so fundamentally that the steering wheel is no longer being grabbed at all. The classical marker is not "I controlled myself." It is "欲念不起" — the wanting *did not arise*. There was nothing to control.

A second scenario: the phone. You pick up your phone to check one message. Twenty minutes later you've been scrolling through outrage content. The 覺觀 here is not dramatic evil — it is the micro-impulse: *one more, one more, one more*. The initial 覺 (flash) is the thumb's automatic swipe; the 觀 (sustained attention) is the twenty minutes of feeding. A person with no concentration practice experiences this as a kind of possession — "I didn't even decide to keep scrolling." A person with genuine samādhi-training experiences something the texts would recognize: in the moment the thumb would swipe, there is a *gap* — not a suppression, but an absence of the compulsion. The four phases (未見: phone is in pocket; 欲見: the itch to check; 見: looking; 見已: having looked) are visible *as phases*, not as a single seamless "I." And in that visibility, the chain can simply... not continue. "不為四運所亂" — not thrown into disorder by the four phases.

A third scenario, harder: parenting. Your child is screaming in a supermarket. Every fiber wants to hiss "Stop it right now" in a voice that will shame them for years. The prātimokṣa layer: you don't hit. Maybe you don't even hiss. But the *wanting to make them suffer for making you suffer* is fully alive. 定共戒 does not mean you feel nothing. It means the wanting does not become *you*. The mind that would narrate "this child is destroying my life" does not get traction, because the mind is not in the mode of narrating. It is in the mode of *being here* — which is, structurally, what samādhi is. You kneel down. You say something. It might not be perfect. But it is not contaminated by the need to punish.

The crucial caveat the texts insist on. You cannot "use" 定共戒 as a technique in the moment of crisis. It is not a tool you grab from a shelf. It is a *state of the mind's infrastructure* that either exists or doesn't, built by months and years of concentration practice. In the moment, what you have is what you've built. T1558's insistence that it is 與心俱 — co-arising with the mind — means it cannot be summoned by will. It is present or absent, like the warmth of a fire. You tend the fire (your sitting practice) in advance; you do not manufacture heat at the moment you're cold.

Why Contemporary People Need This

1. The crisis of "white-knuckle morality." Contemporary ethical life is largely prātimokṣa-shaped: rules, policies, compliance training, terms of service. You agree not to do things. And then you do them anyway, in private, in the browser tab no one sees, in the thought you'd never voice. The result is a culture of *mixed* precept-keeping — 雜, in T1911's word. Outer compliance, inner chaos. People experience this as hypocrisy, and the hypocrisy exhausts them. 定共戒 points to something else: a purity that is not *enforced* but *structural*. Not "I must not want this" but "the wanting has gone quiet." This is not moral perfectionism. It is the recognition that a mind trained in stillness *behaves differently by nature*, the way a river that has found its channel doesn't need levees.

2. The attention economy as 覺觀 amplification. Every app on your phone is an 覺觀 machine: it generates the initial flash (notification, red badge, headline) and then feeds the sustained rumination (infinite scroll, algorithmic recommendation). The classical framework says: if your mind is in a state where 覺觀 cannot chain — where the flash does not become the twenty-minute spiral — you are, functionally, in the neighborhood of 定共戒. You don't need to be in formal meditation for this to matter. The *residue* of samādhi — what T1911 calls "出定身口柔軟，亦不雜" ("after leaving absorption, body and speech are soft, and also unmixed") — is what lets you put the phone down. Not willpower. Residual stillness.

Contemporary neuroscience has a partial parallel here: research on default mode network (DMN) activity suggests that experienced meditators show reduced DMN activation and weaker coupling between DMN and attention networks, which correlates with less mind-wandering and less "sticky" reactivity. But the parallel is *partial* and must be stated with its limits: fMRI studies of meditators show correlation, not the causal mechanism the Buddhist texts claim; sample sizes are often small; "reduced DMN activity" is not the same as "desire does not arise"; and no brain-imaging study can confirm or deny the soteriological claim that this stillness is a *precept* — a moral achievement, not just a neural state. The science is suggestive of the *substrate*; it is silent on the *meaning*.

3. The gap between knowing and being. Contemporary people are the most *informed* moral agents in history. We know what fast fashion does. We know what our attention does to our children. We know what outrage media does to our politics. And we do it anyway. The gap is not informational. It is *volitional* — the 覺觀 runs ahead of the knowing. 定共戒 addresses exactly this gap. It says: the problem is not that you don't know the rule. The problem is that the part of you that would *obey the rule* is not the part that is *running the show* in the hot moment. What you need is not more information. You need a mind that has been restructured so that the knowing and the doing arise from the same still point. "依因此戒，能生禪定及滅苦智慧" — "Depending on this precept, samādhi and the wisdom that extinguishes suffering can arise" (T1911, citing sūtra). The precept is not the end. It is the floor from which the rest of the path becomes possible.

4. Against the "spiritual bypassing" reading. It must be said clearly: 定共戒 is not an excuse to skip ethical effort. The texts are adamant: "尸羅不清淨，三昧不現前." If your behavior is a mess, you will not get the samādhi that generates 定共戒. You cannot meditate your way out of being a person who harms others. The sequence is: clean up your actions first (律儀戒) → that cleanup removes the gross obstructions (事障) → concentration becomes possible → in concentration, the deeper obstructions (性障) quiet → 定共戒 arises → from that platform, insight (慧) becomes possible → 道共戒, the irreversible purity of the path, dawns. Skipping step one and claiming step four is not Buddhism. It is delusion with a cushion.

Common Misreadings and Clarifications

Misreading 1: "定共戒 is just 'being mindful.'" Mindfulness (念, smṛti) is a factor *within* the concentrated mind, but 定共戒 is not mindfulness per se. Mindfulness can be present in a scattered mind — you can be "mindful" of your anger while still being *in* the anger, still narrating, still planning revenge. 定共戒 requires the mind to be in a qualitatively different *state* — one where the discursive elaboration (覺觀) has structurally ceased. The difference is between watching a storm from a window and being in a room where the storm cannot enter. T1716's phrase "屬止善義" — "belonging to the goodness of *stopping*" — is key. This is śamatha (止), not vipaśyanā (觀). It is the stillness that makes the precept possible, not the awareness that observes the breach.

Misreading 2: "If it can be lost, it's not real." The fragility of 定共戒 — its dependence on a samādhi that can regress — troubles people who want moral achievement to be permanent. But the tradition's honesty here is its gift. It says: *states* are not *attainments*. You can touch a purity in meditation that you cannot yet sustain in life. That touched purity is real — it is not fake, not pretend. But it is not yet *you* in the way that stream-entry makes the path-precept (道共戒) irreversible. The correct response to this fragility is not despair ("what's the point if I'll lose it?") but diligence: return to the cushion, rebuild the samādhi, let the precept re-arise. Each time, the groove is deeper. The texts' unresolved debate about whether 定共戒 persists after leaving absorption is itself a teaching in non-attachment to states: don't cling to having-had-it; don't deny that it was real.

Misreading 3: "定共戒 means you never have a bad thought again." No. It means that *in samādhi*, the bad thought does not arise, and that the *residue* of samādhi softens the post-meditative mind ("出定身口柔軟"). It does not mean the latent tendencies (隨眠, anuśaya) are destroyed. That is the work of 道共戒 and the path of seeing (見道). A person with 定共戒 can still be irritated, can still feel the first flicker of greed. What has changed is the *chain*: the flicker no longer automatically becomes a story, a plan, an action. The 四運心 framework makes this precise: you see 未見 → 欲見 → 見 → 見已 as discrete, findable, *empty* phases. The chain is visible, and therefore breakable. Before samādhi-training, the chain was invisible, and therefore unbreakable.

Misreading 4: "This is only for monastics or advanced meditators." T1911 explicitly says: "凡夫入定則能持得也" — an ordinary person can hold this. The threshold is not sainthood; it is *genuine access concentration*. This is available to anyone who sits regularly and honestly. What is *not* available is the shortcut: you cannot get 定共戒 from a weekend retreat app, from a YouTube video on "calm," or from reading about it. It requires the accumulated hours of letting the mind learn, in its own body, what non-grabbing feels like. The texts' insistence on 根本禪 and 近分定 as the locus of arising (T1558: "從根本恒時，得靜慮無漏") is a realism about the depth of stillness required. Shallow relaxation is not samādhi. Samādhi is a specific, identifiable, trainable state in which the five hindrances (五蓋) are genuinely suppressed, not merely distracted from.

Misreading 5: "定共戒 is 'natural morality' — you just follow your instincts." The opposite. "Natural" in the contemporary romantic sense (follow your feelings, trust your gut) is precisely the 覺觀-driven life that 定共戒 *replaces*. The "naturalness" of 定共戒 is the naturalness of a river that has been *dredged and channeled* — it flows without effort, but only because enormous prior work made the channel possible. The 性戒 (xìng-jiè, "nature-precept") that T1911 identifies as the foundation ("通以性戒為本") is not "whatever feels right." It is the intrinsic moral structure of reality — the fact that harming creates suffering, that generosity creates freedom — which the concentrated mind *sees directly* rather than obeying as an external command. The precept is "natural" in the way that seeing is natural to an open eye: not because the eye *decides* to see, but because the obstruction (the closed lid) has been removed.

Misreading 6: "Science has proven this." It has not. Neuroscience can show that long-term meditators have different brain activation patterns, thicker prefrontal cortex, reduced amygdala reactivity. These are *correlates* of the state the texts describe. They cannot establish the normative claim — that this state is a *precept*, a moral achievement, a necessary stage on the path to the cessation of suffering. They cannot establish that the "desire not arising" reported by a meditator is the same event as "reduced amygdala activation." They cannot establish the soteriological framework — that there *is* a path, that it has stages, that this is one of them. To cite neuroscience as "proof" of 定共戒 is to commit a category error: the texts are making a first-person, normative, soteriological claim; the science is making a third-person, descriptive, correlational claim. They can be *compatible*. They are not the same claim. Honesty requires saying: the science is interesting, it is suggestive, and it is *not yet* a confirmation of the Buddhist framework. The framework stands or falls on its own terms — in the first-person laboratory of sustained practice.

A Final Word on Where This Sits in the Whole Path

The genius of 定共戒 as a concept is that it names a *middle* that our moral vocabulary usually misses. We have "rules" (external, enforced, often resented) and we have "enlightenment" (total, irreversible, seemingly impossibly far). Between them yawns a gap where most spiritual life actually happens: the long, unglamorous work of training the mind to be still, and discovering that stillness *changes how you behave* in ways that willpower never could. 定共戒 is the name for that discovery. It says: there is a form of goodness that is not obedience. It is not yet freedom. But it is real, it is available, and it is the indispensable bridge between the person who white-knuckles through the precepts and the person for whom harming has simply become impossible.

"依因此戒，能生禪定及滅苦智慧." Depending on this precept, samādhi arises. Depending on samādhi, the wisdom that ends suffering arises. The precept is not the destination. It is the ground under the first real step.