The koan is a special form of the anecdote of Zen Buddhism, all of which seems pointless and paradoxical. They are given to Zen students who often ‘work’ on a solution for years, even though everyone knows that there is no solution in the traditional sense. What exactly is behind this seemingly strange practice?
Brief introduction to Zen
Note: This article is part of a series of articles that outline some of the basics of Zen Buddhism.
In Western terms, koans (actually kōans) are something like trick questions, riddles, paradoxes, et cetera. As a strange spiritual cultural asset of Japanese Zen, it was never taken seriously in Western philosophy because it goes beyond the means of any logic. Examples of koans are common:
- What was your original face before your father and mother put you in this world?
- A long time ago a man kept a goose in a bottle. It grew and grew, and in the end it never came out of the bottle. The man didn’t want to smash the bottle or injure the goose. How can he get the goose out?
- A man has climbed a tree, clinging to a branch with just his teeth while his body dangles freely in the air. Another, standing below, asks him, “What is Zen?” If he gives an answer, he can satisfy the questioner. But if he only speaks a single word, he must let himself fall. What would you answer him?
We too will naturally have problems understanding what a koan is and what it exists for, if it has any purpose at all. It is therefore advisable to begin briefly with the background of Zen in order to get a feel for this domain in the first place. At this point I have already written an introduction to Zen that you can read in addition to this article.
It is customary to begin the history of Zen with Bodhidharma , the first patriarch of Zen, who “introduced the character and attitude of Zen Buddhism to China […] in the year 527” .
The reigning emperor of China at the time, Wu von Liang, was known as a venerable advocate of Buddhism and invited the monk to his court. The following legendary dialogue between Emperor Wu and Bodhidharma first illustrates the split between Zen and Buddhism through the strict rejection of the karma doctrine.
In its deeper sense, it also reveals the embodiment of the essence of Zen. Emperor Wu wanted to know what to expect from his piety:
“Therefore he asked Bodhidharma: ›› We have built temples, copied holy scriptures, ordered the conversion of monks and nuns. Does our conduct, venerable master, deserve any credit? ‹‹
Bodhidharma: ›› No merit. ‹‹
The emperor, a little baffled, thought that such an answer would overturn the entire teaching and asked again: ›› What is the holy truth, the supreme principle? ‹‹
Bodhidharma: ›› That principle is in everything; there is nothing sacred. ‹‹
Emperor: ›› Who are you who stand before me? ‹‹
Bodhidharma: ›› I don’t know, your majesty. ‹‹ “ (ibid.)
From Buddhism to Zen
Bodhidharma’s answers coined the Zen saying “Open space, nothing sacred” , which marked the first step to do away with the metaphysical speculation of Buddhism.
In this context, it is interesting to note how Buddhism was first replaced by the various Hindu traditions that are summarized as Hinduism by largely dispensing with metaphysical speculations  and then a few centuries later the same thing with Buddhism by splitting off Zen happened.
I cannot explain the reasons for this here, but it should be pointed out that Zen is an independent form of life and the term Zen Buddhism only indicates that Zen is a movement that emerged from the Buddhist tradition .
In the form of the main stream, namely Japanese Zen , it can hardly be compared with classical Buddhism. The sentence derived from Bodhidharma may seem nihilistic at first, but this is simply a common misinterpretation.
On closer inspection it becomes clear that everything that Zen Buddhism implements shows itself in the fact that it “turns the Buddhist religion into immanence in the most radical way” .
There is no transcendence and therefore no escape from the world – this alone also forms the essence of Zen meditation (Japanese zazen), namely the turning to the moment, into the infinite immanence in the here and now.
The world and the self are accordingly “emptied of all theological-teleological ‘meaning'” (ibid.) And are likewise “neither occupied by theos nor by the anthropos” (ibid.). They neither focus on the idea of God nor the idea of the human.
This brings us to the core concept of Zen, namely emptiness, the absolute nothingness or Śūnyatā, which is related to the world and the self in the following context:
“The concepts of the world and of the self interpenetrate one another in Zen Buddhism, whereby this interpenetration in turn consists of absolute nothingness [sansk. Śūnyatā, Japanese Mu] is penetrated. In the picture of the empty circle [jap. Ensō] […] this is well expressed. […] The self is therefore in a space which in turn is ultimately encompassed by the infinite openness. This entire structural complex belongs to the self as such. ” 
The way to the true self
Emptiness is the opposite of substance, but not to be understood as the mere absence of substance. The latter is, as it were, full and designed to be closed . In complete contrast to this, Śūnyatā is “a movement of disqualification” (ibid.), Which empties beings.
In this sense, there is no true separation of things, since everything can be traced back to emptiness, which in no way should be understood in such a way that Śūnyatā is a principle of origin from which all that beings arise (cf. ibid.).
By emptying the being as a movement, which clings to its substance and thus remains within itself, emptiness sinks “it into an openness, into an open expanse” (ibid.). This would complete Bodhidharma’s above-mentioned sentence.
Zen practice is all about making this happen. Radical subjectivity and lack of understanding (Japanese: Mushin) are the focus of the implementation, as the focus on something outside of the self, as well as the adherence to logic and the conceptual only distract from the immanence, i.e. the here and now. If one is granted this realization, one attains enlightenment (Japanese satori), ie one gains one’s true self :
“Satori is a specific experience in terms of the way it occurs and its effect on character. Otherwise it remains indefinable, unpredictable; for it is the sudden realization of the truth of Zen. By its nature, satori is an unexpected experience. “ 
The koan as a yardstick
Describing the Koan practice of Zen is a difficult and even impossible undertaking. Trying to shape it into language may sound simple, but in the experience of reality it is anything but that.
The unmistakable experience of satori is now considered the benchmark for Zen. Furthermore, the koan is the yardstick for the satori (cf. ibid.). The koan “is something like a problem that the Zen master presents to his students for a solution” , but at the same time it is something that “is within us and everything that the Zen master does, is to show it to us so that we can see it more clearly than before ”(ibid.).
This something in us is the paradox of life, the dualistic contemplation of the mind and the desperation with the world inherent in the human condition . Each koan confronts the Zen student with this fact and stirs up great doubts in him or even resignation .
A popular koan reads: A sound is produced when two hands are clapped together, which sound is produced when one hand is clapped together? Every koan shows that “there is usually a choice between an either and an or, but one of which is as impossible as the other.” 
The choice is to hold on to the world, thereby not gaining salvation from conflict with it (clapping both hands) or being crushed by the paradox of the world (clapping one hand). You have to find a way past yes and no. The koan is supposed to teach how this can be possible by teasing out a certain mental attitude in the student that cannot be described in words. That takes a lot of patience.
Therefore each koan reflects the immense koan of life; for, for Zen, the problem of life lies in getting beyond the either / or, the opposition of yes and no, which both obscure the truth. (ibid.)
At the moment when the student overcomes despair, the “satori flash” (ibid.) Comes, that is, that experience which resolves the eternal dilemma between yes and no, between thesis and antithesis, in short between every dualistic attitude.
At this moment the human condition breaks : The satori man, the enlightened one , is one with the world, yes he understands that one can never really be separated from the world and what a valuable game life as a whole actually is.