Koans are the special short questions of spiritual masters in the Chan and Zen traditions. (Chinese Chan became Japanese Zen). Some seventeen hundred koans have lasted for over a thousand years and have been itemized in various collections.
Koans are used to move students beyond reason, rationality, and discursive thought and take them to a higher level of intuitive comprehension. The surface meaning of the koan is meaningless, not syntactically but in terms of ordinary rational understanding.
Consider this ancient koan: 'What was the shape of your face before you were conceived?'
Syntactically, this is workable sentence, but it is hardly one that anyone would utter as a rational query. And so, as the student answers the koan, he is not at all tempted to seek and offer a rational reply: 'I had no face prior to conception. May I go now?'
The student must seek another type of path to another type of answer. The answer to the koan, in Japanese called the watō and in Chinese it's called the huatou, is just as illogical as the query. Actually, there is no one answer, no one watō, and the answer given is deemed right or wrong by the master.
'My face was the pale Amur.'
'Never was treasure lost or found.'
'I as soft sand sift through fingers.'
These are all watōs. Perhaps! It is for the Zen master to decide.
Now, let's step back and ponder Zen, a spiritual tradition that does not generally esteem words, or thought, or philosophical conundrums, or psychological reverie. Zen is meditation eventuating in buddahood. Mediation upon airy nothing.
And yet Zen finds in words needful things: spiritual filigree, pious stepping stones, a meditative lattice. Zen wants to get beyond words and common logic but it cannot. Zen wants to get to a point where speech exhausts itself but it cannot. The super-sensual a-rational intuition that Zen celebrates cannot rid itself entirely of rationality.
After all, the koan was not constructed thus: 'Shape were was of face what the before conceived you your?' All the words of the original koan are there. Why not use them in this order? In a system that wants to get beyond words, why isn't gibberish the medium of enlightenment?
This should remind us of mystics who claim an ineffable experience and then compose well-written inch-thick books describing the experience.
And so we see: No practice of meditation or mysticism can dodge the need for syntactically correct, rational words in a row.