What This Concept Is Saying
Let us first look at the complete provenance of this concept. Chan master Caoshan Benji 曹山本寂 divided the "different class" (异类, yìlèi, "the alien class") within the Chan school (宗门, zōngmén) into four kinds, called "Caoshan's Four Different Classes" (曹山四异类): "walking within the different class" (异类中行), "dwelling within the different class" (异类中住), "lying down within the different class" (异类中卧), and "emptiness within the different class" (异类中虚). What we discuss today is the fourth—the highest and the most difficult to understand—"emptiness within the different class."
The definitional clue given in the source material is extremely terse: "禅门中见解偏异而不契宗旨者"—one in the Chan school whose views are deviant and who does not accord with the school's essential aim. This is stated from the negative side—those whose views have gone astray and do not correspond to the school's intent are called "the different class." But this sentence only gives half of what "different class" means. The complete structure of Caoshan's Four Different Classes tells us that "different class" in the Chan school has two faces: one is illness, the other is medicine.
The face of illness is "views that are deviant and do not accord with the school's essential aim." A person studies Buddhism and Chan and ends up with a strange set of views, departing from the middle way (中道, madhyamā-pratipad, "the middle way"), falling onto some extreme—either clinging to emptiness (执空), or clinging to existence (执有), or clinging to "non-discrimination" (无分别, nirvikalpa) while discarding "discriminating wisdom" (分别智), or clinging to the "ordinary mind" (平常心) while discarding "the power of diligence" (精进力, vīrya). This kind of deviation is what the school rebukes and corrects.
The face of medicine is just the opposite: the true ancestral masters, in order to break students' attachment to "normal," deliberately "walk within the different class." The words of Chan master Nanquan Puyuan 南泉普愿 expose this secret:
「智不到处切忌道著，道著则头角生。」 *"At the place where wisdom does not reach, be careful not to say it out loud—say it out loud and horns grow."*
"Where wisdom does not reach" (智不到处)—this is the boundary of cognition. Ordinary people use consciousness to reason, use concepts to frame, use language to speak; but the ultimate thing that Chan speaks of lies precisely at the end of all this "wisdom." It is not an object of wisdom, not prey that thinking can capture. "Be careful not to say it out loud"—when you get to that place, you must be cautious; it cannot be spoken. The moment it is spoken, "horns" (头角) grow.
What are "horns"? Ox horns, goat horns. When an ox grows horns, you can recognize it as an ox at a glance; once a concept is spoken, you can recognize it as a concept at a glance. So "say it out loud and horns grow" means: the moment you open your mouth and say "it is this," it immediately becomes "this," and grows "horns" that can be recognized, grasped, and classified.
Nanquan continues: 「唤作如如早是变。」 *"Call it 'suchness' and it has already changed."* You hear what was said before and think: "Fine, I won't say what it is; I'll just call it 'suchness' (如如, tathatā)." Nanquan says: no. The very act of calling it "suchness" is already a change. The name "suchness" is itself a concept; the moment this thought arises, the ineffable thing has already been translated, refitted, and reduced in your mind. It is like reaching out to grab water—the moment your fingers close, the water has already slipped through them; all you have caught is the gesture of "grabbing" itself.
Then what to do? Nanquan says: 「须向异类中行。」 *"You must walk within the different class."* You must go into the "different class." Here, "different class" does not refer to some strange kind of being, but to: the position that belongs to no category, that does not fall within any framework of names and forms (名相). You can no longer be a "normal practitioner"—because "normal practitioner" is a category, and a category means it can be defined and framed. You must walk beyond all categories.
But here is the problem: once you "walk into the different class," have you not fallen into the category of "different class"? Caoshan therefore calls this state "emptiness within the different class"—within the different class, it is also empty. "Different class" itself is also false, also just a name. You walk within the different class, and at the same time know that "different class" is unobtainable—this is "emptiness."
So the structure of this concept is:
- Illness: views that are deviant and do not accord with the school's essential aim are called "different class" (this is the negative sense, needing correction) - Medicine: in order not to fall on any side, one actively walks within the different class (this is the positive sense, the great capacity and great function (大机大用)) - One level deeper: even the name "different class" is not grasped; walking within the different class while knowing that its characteristics are originally empty—this is "emptiness within the different class"
The source material also has a very important definition: "禅门中见解偏异而不契宗旨者"—one in the Chan school whose views are deviant and who does not accord with the school's essential aim. This reminds us that "different class" in the school's everyday usage is first of all a critical designation. But the fact that Caoshan lists "emptiness within the different class" as the last of the four different classes precisely shows: the true different class is not the person who falls into some bizarre view, but the one who does not even dwell in "different class" itself. Illness and medicine merge in this final layer.
Walking Through It in Daily Life
Let us walk this concept through the daily life of a contemporary person.
Scenario one: you are scrolling on your phone on the subway. You see a notification: "What is the meaning of life?" You tap in, read for three minutes, swipe away. Then the next one: "This restaurant is a must-eat!" You tap in again. Your mind switches between "meaning" and "food," and every thought lands within some categorical framework. You have never had the experience of "where wisdom does not reach"—because you have never been to the boundary of "wisdom." You have stayed in the comfort zone of "wisdom," weaving your day with concepts, judgments, likes, and dislikes. There is nothing wrong with this, but you should know: you have never attempted "walking within the different class."
Scenario two: you begin to study Buddhism. You hear "don't cling," so you try hard not to cling. But you quickly discover that "not clinging" becomes a new clinging—you cling to "not clinging." You eat with friends, a friend orders a meat dish, a thought arises in your mind: "I'm not clinging," and you eat it with peace of mind. But there is actually a subtle voice inside you: "I am more advanced than them, because I have learned 'not clinging.'"—this is "views that are deviant and do not accord with the school's essential aim." You have turned "not clinging" into a view, a label, a self-image that makes you feel good. This is "say it out loud and horns grow"—the moment you say "I am not clinging," the sentence grows horns and becomes an identity you can grasp.
Scenario three: you read Nanquan's words and think they make sense. You think: "Fine, I won't say 'I am not clinging.' I won't say anything." You sit there, trying to experience "where wisdom does not reach." But you immediately discover: you are "trying to experience," and this "trying" itself is a thought. A voice inside says "I am now experiencing the place where wisdom does not reach"—the moment this voice appears, you are already no longer there. This is "call it 'suchness' and it has already changed." You call that experience "suchness," "emptiness," "the original face"—every naming is a deformation, and every deformation takes you one step further from it.
Scenario four: you are completely disheartened. You think: "Forget it, I can't do anything." You decide to give up practice and go back to scrolling on your phone. But this is precisely the biggest misunderstanding. Nanquan says "you must walk within the different class," not "return to the category of the ordinary person." The ordinary person is also a category. Going back to scrolling is just jumping from the category of "practitioner" back to "ordinary person"—you are still spinning within categories. The different class is neither ordinary person nor practitioner, not any existing category. "Walking within the different class" means: you live out a state that no category can frame. The ordinary person scrolls on the phone—that is "delusion" (迷); the practitioner sits in meditation—that is "cultivation" (修); but the person who "walks within the different class" may be scrolling or may be meditating, yet their mind does not fall on either side of "scrolling" or "meditating"—they simultaneously know that all of this is empty.
The easiest place to mis-map: many people understand "walking within the different class" as "being unconventional," "not playing by the rules," "breaking the mold." This is not what Chan means. Being unconventional is still a category—"the unconventional person" is an identifiable category, and you are still within a category. The true "walking within the different class" is not behavioral strangeness, but the mind's not falling into any framework. You can wear the most ordinary clothes and live the most ordinary life, but your mind does not cling to the concept of "ordinary"; you can also wear outlandish clothes and do shocking things, but your mind does not cling to the concept of "extraordinary." The former is "walking within the different class"; the latter is just an ordinary person who has changed categories.
Let us walk through one more detail: what is "where wisdom does not reach"? In the contemporary context, we can say: it is the place that no algorithm can predict. When you scroll through short videos, the algorithm predicts what you will like, how long you will stay, where you will swipe away. Every time you press "next," it is the algorithm's "wisdom" operating on you. But one deep night, you suddenly put down your phone, look at the streetlight outside the window, and a feeling rises in your heart that cannot be put into words—that feeling belongs to no category, and the algorithm cannot predict where it comes from or where it goes. In that moment, you touched "where wisdom does not reach." But you must be careful: the moment you think "I just touched the place where wisdom does not reach," you have already left that place. This is "say it out loud and horns grow."
Why Contemporary People Need It
We live in an age of over-classification. AI is classifying us—are you a "high-net-worth user" or a "price-sensitive user"? Are you "Gen Z" or "Millennial"? Are you a "content creator" or a "content consumer"? Every classification is a horn; you have been labeled, and you have labeled yourself. The content you see, the friends you make, the jobs you find—all are pushed to you by algorithms according to categories. Your "self" increasingly resembles a classification table—you find your position in that table, then strive to play the part that position is supposed to play.
The deepest pain of this age is not too few choices, but too many categories. You are stuffed into countless categories, and each one demands you grow a pair of horns to prove your belonging. You have lived into a person covered in horns—every horn is an identity, a label, a self-definition of "I am."
"Emptiness within the different class" is the best antidote for this age. It is not asking you to reject all categories—that too is a category ("the person who rejects categories"). It is not asking you to give up the self—that is nihilism. It lets you see: all categories are products of "wisdom," and the true you lies precisely at "where wisdom does not reach." You do not need to become a member of any category; you only need to live out that which is not framed by any category. That itself is "empty" (虚)—not "nonexistent," but "not substantially real": it cannot be grasped, cannot be named, cannot be classified; yet it is always there, beneath all your categories, behind all your labels, before all your "I am."
What contemporary people most need is this experience of "emptiness." You are not your job, not your income, not your marital status, not your personality test results. And you are not merely "none of the above" either—that again becomes a category. You are that which is outside all categories, yet does not reject any category: alive, present, ineffable. Chan calls this "emptiness within the different class." Contemporary people need it because it can liberate you from the suffocation of "being classified."
Common Misreadings and Clarifications
Misreading one: "different class" means "weird." This is the most common misreading. When people see the two characters "different class," they think it means behaving strangely and being unconventional. But the "different class" in the Chan school is precisely not "abnormal" as opposed to "normal"—because "abnormal" is still the counterpart of "normal," still falling within a dualistic category. The true different class transcends the binary pair of normal and abnormal. It is not "weird," but "unclassifiable."
Misreading two: "where wisdom does not reach" means "don't think." No. "Where wisdom does not reach" speaks of what lies beyond the limit of thinking; it does not mean stop thinking. Chan never forbids thought—on the contrary, the repartee and exchanges of Chan are extremely precise intellectual activities. The problem is not thought itself, but treating thought as the only tool. When you use thought to grasp the thing beyond thought, you are doomed to fail; but you cannot therefore say thought is bad. Thought is a tool, not the master; it is a finger, not the moon.
Misreading three: "walking within the different class" means "not being a normal practitioner." Some people hear "you must walk within the different class" and think they should give up meditation, give up the precepts, give up the scriptures, and do things that do not conform to convention. This is a great error. "Walking within the different class" is not behavioral rebellion, but transcendence in mind. You still meditate, still uphold the precepts (持戒, śīla), still read the scriptures, but you do not cling to the category "I am a practitioner." Conversely, if you deliberately break the rules and deliberately act against convention in order to "not be a normal practitioner," then you have precisely fallen into the category of "anti-practice"—you are still within a category, just having grown a different horn.
Misreading four: "emptiness within the different class" is nihilism. Some people see the character "empty" (虚) and think it means nothing at all, nothingness, giving up everything. But the Chan "emptiness" is not nothingness; it is "not substantially real"—it does not deny the existence of phenomena, but denies that phenomena have a fixed, unchanging self. The phone before your eyes is real, but the concept "phone" is an expedient designation, not substantially real. You, this person, are real, but the concept "I" is an expedient designation, not substantially real. Emptiness is not "there is nothing," but "there is nothing to cling to." Walking within the different class while knowing that the different class is originally empty is the highest freedom—you negate nothing, and are bound by nothing.
Misreading five: "be careful not to say it out loud" means "don't speak." No. The ancestral masters of Chan talk all day; their recorded sayings fill volumes. "Be careful not to say it out loud" does not mean "shut up," but "do not think that what is said is that thing." You speak, but you know the words are not that thing; you listen to others speak, but you know that thing is not in the words. Speech is the finger pointing at the moon—you follow the finger and see the moon, but you do not cling to the finger itself. This is the correct way to "say it out loud": say it, but do not let it grow horns; hear it, but do not let it become a frame.
Finally, let us take the line from the Heart Sutra (心经) as confirmation: 「照见五蕴皆空，度一切苦厄。」 *"Illuminatingly perceive that the five aggregates are all empty, and transcend all suffering and distress."* The "five aggregates" (五蕴, pañcaskandha) are categories; "illuminatingly perceive" (照见) is wisdom; "empty" (空, śūnyatā) is emptiness. When you illuminate and see that all categories are empty, not substantially real, not graspable, you are no longer trapped by any category—this is the corresponding expression of "emptiness within the different class" in the scriptures. It is not the strange talk of some eccentric, but an important signpost on the entire Buddhist path of liberation: at the end of wisdom, put down wisdom; at the end of speech, put down speech; at the end of categories, put down categories. Then, in all places, at all times, you are that unclassifiable, alive, free itself.