Even though Ganhwa Seon was a method of practice perfected in the Song, this method itself was not completely new. Hwadu has a strong power that blocks the exits for all thinking. The structures of such hwadu are closely connected with the structure of the Middle Way and the conditional production preached by the Buddha.
To the question, “Does a dog have the Buddha-nature,” Zhaozhou replied, “It does not (mu).” This mu reply understood in the speculative formula of the four alternatives of 1) it has, 2) it has not, 3) it does and does not have, and 4) it neither has nor does not have, is mistaken. The form of the above four sorts of thinking are called the tetralemma. Not only are not even one of these forms of thinking recognized by the hwadu of mu, but also thinking itself is not permitted.
In this respect, Seon Master Dahui said,
If one is not attached to existence, then you are attached to non-existence (mu), and if you are not attached to either, then you are discriminating and comparing existence and non-existence. Even if one senses this disease, one soon ends up being attached to neither existence nor non-existence. For this reason former saints said, “Get rid of the tetralemma, put an end to the hundred denials. Directly break a sword into two pieces and do not think again of fore and aft, and just cut off the forehead of the thousand saints.” The tetralemma refers to the four (propositions) of existence, non-existence, neither existent nor non-existent, and while existent is non-existent. (Shuzhuang, Reply to Judicial Commissioner Zhang).
Seon Master Dahui asserted that practice must transcend the tetralemma. Also, the words “one hundred denials,” being applied as an extension of this concept of the tetralemma, means something similar to the tetralemma. Not only Seon Master Dahui, but also various Seon recorded sayings strongly assert one should transcend the tetralemma and hundred denials.
Let us look at the words of Mazu.
A monk requested the teaching, “Seon Master, tell me the meaning of the Patriarch coming from the West without using the tetralemma.” (Mazu yulu)
The practitioners of Ganhwa Seon sit and face a hwadu like silver mountains and iron walls that block all the exits of tetralemma-like discrimination. If so, let us examine how being apart from the tetralemma and the hundred denials can be in agreement with the structure of the Middle Way and conditional production.
The principle of conditional production is no different to the principle of the Middle Way. The Middle Way is a direct viewpoint about the universe and life that looks at them as being this and that as they are from the position that has abolished this and that. So the Middle Way is nothing more than the concept that means something between this and that. This way is wrong and that way is wrong. We cannot express this through speech or writing. At that time, our thoughts fall into the condition where it cannot be like this and cannot be like that. It means one cannot budge in the least, just like a mouse in a pitch-black box.
The Middle Way are words that inform one of the proper features of the Dharma-realm which is apart from this or that simultaneously. It is not easy to be enlightened to the principle of this Middle Way. The principle of the Middle Way cannot be realized through any cogitative discrimination that something is or is not.
The bodhisattva Nagārjuna (ca.150-ca. 250) was a Buddhist patriarch who wrote the Mahyamikakārika in order to re-clarify the essential doctrines of the Buddha-dharma. This Mahyamikakārika never approved of a tetralemma-like reply to the questions that it posed.
Therefore, the practice-method of Ganhwa Seon is the same in content and structure as the Middle Way and conditional production preached by the Buddha, and the tetralemma discrimination and eight-fold negation Middle Way of the Mahyamikakārika. All of these have the same aim, from the point of leading us towards the world of enlightenment by the cutting off of our discriminatory thinking.
Besides the Sixth Patriarch, Huineng and Seon Master Dahui, many other patriarchal monks consistently said one should to stand directly in the Middle Way and apart from the two sides.
Seon Master Dazhu Huihai said, “If one is not attached to existence and non-existence that is seeing the Buddha.”