The entering into and producing of a doubt about the hwadu is the investigation of the hwadu. Only when the doubt is penetrating and one is in a condition of when only doubt is lumped firmly together, is the hwadu taken up well. What should one do to produce doubt by taking up the hwadu?
Let us try to explain it through the example of hwadu that are most often used, the hwadu of the “character mu” and the hwadu of “What?” One either takes up the entire proposition attached to the front of the “mu character” hwadu, or just the mu itself, although it is a bit vague. The entire proposition means the entire content related to the hwadu.
Let’s take up the example of the hwadu of the character mu:
A monk asked, “Does a dog have the Buddha-nature?”
Zhaozhou replied, “It does not (mu).”
The Buddha said, “All sentient beings have the Buddha-nature,” so why did Zhaozhou say the dog does not have the Buddha-nature?
The lines quoted above are the entire proposition concerning the hwadu of the character mu, that is, the entire content. On the other hand, the lone proposition is explained as “mu” or “why did he say mu?” When one starts to meditate, although at first the entire proposition and the lone proposition are used mixed together, if one becomes versed in it, the entire proposition is burdensome. If one is familiar with it, the entire proposition enters totally into the lone proposition. Automatically it then becomes the lone proposition.
The essentials of investigation are thus:
“Does a dog also have a Buddha-nature?”
“Why say no?”
Likewise with the hwadu, “What is it?” (i-mwot-go)
“What is that fellow who eats, wears clothes, talks, looks and hears, the governor who is bright and numinous whenever and wherever?”
“It is not mind, not Buddha, not a single thing. What is it?”
“Before my parents were born, what is my original face?”
“What is the fellow who pulls along this lump of a body?”
For the hwadu, “What is this?” one should select just one of the various hwadu above and it may create doubt. If one tries to expand it by just one more, when one takes up the hwadu through the entire proposition, one must take up only one entire proposition. Of course there are no differences of superiority or inferiority between these entire propositions. One should select only one and earnestly take it up. A possible tip for practicing a hwadu is, when one takes up “What is it?”, one must give rise to doubt, while making ‘this’ (i) slightly long, mentally that the fellow who is doing the ‘this’ is ‘what?’. Or, although it is a bit vague, one would lengthen and sophisticate the doubt by making the hwadu lengthened like ‘this (i) – what (mwot) – is (go)?’. The essential though is to have it earnestly. If one must make the entire proposition, this must become simple not become the source of delusion.
When doubt does not emerge well, one takes up the entire proposition again and again, one (asks) “What is the fellow that moves this body?” and there is no other clever plan but to endlessly take up hwadu. Endlessly, one must enter into them earnestly and intensely.
If one tries to investigate hwadu in this way, one must have an extremely earnest mind. Just as in a desert, feeling thirsty one only thinks of water. A birth mother who sends her only sons to the warfront, day and night thinks of her children. Likewise, one must have a mind of urgency that investigates only one hwadu. Such an urgent mind occurs when one stakes one’s entire life on it. If one tries to take up the hwadu this earnestly, one day suddenly a genuine doubt occurs, and the hwadu vividly manifests itself in front of one. At such a time the mind internally becomes calm, and the illusions of frustrations also automatically disappear.
In truly devoting one’s life and proceeding by controlling it thought by thought, this study has difficulties. If one completely believes that one is originally Buddha and does not look forward or back, since I have departed from the same conditions as all teachers of the past, and so I also am diligent, it is sure that I will be thoroughly and greatly enlightened (hwakcheol daeo), and can see the nature and become Buddha. With this thorough faith, one must vigorously advance in practice.