The cardinal point of hwadu study is to take up a hwadu that has no path to grope for or seek, and to earnestly give rise to doubt and smash that doubt. One must not open up and use any rational thought at all. In the condition in which thought is thoroughly intercepted, there is entry into and doubt about hwadu. If one chants the hwadu that one has to doubt in this way as if one was chanting the name of the Buddha, this is the casting off of the original path of the investigation of the hwadu. Thus even if one is not possessed by the hwadu, one must not use mantic power or chanting of the hwadu or being mindful of the hwadu.
Chanting hwadu (song hwadu) is making the sound of the hwadu such as “What is this?” or the character mu and to endlessly and continuously recite it. For example, saying “What is it?” “What is it?” “What is it?” or “mu” “mu” “mu” is the continuous recital without any doubt.
Mindfulness of hwadu (yeom hwadu) is not making such sounds of hwadu as “What is it?” or “mu”, but reciting it in the mind. When one takes up Zhaozhou’s mu character hwadu, this is taking it up just repeating “mu” “mu” without any doubt. But whether or not one makes the sound or not, when one looks at it in Ganhwa Seon, this is a mistaken method. No matter when one is going on the path, it is mu, when sitting is mu, when wearing clothes and eating food is mu, no matter whether it is mu at any time, this method is not a proper method of taking up a hwadu. And even more, one must not use thought to think of mu.
Mantic power is the chanting of “Om mani padme hum” or the Dharani of the Gwaneum Bodhisattva of a Thousand Hands or the Lengyanjing mantra. Because these incantations are the mysterious words of the Buddha, one can gain power through chanting them. But in Ganhwa Seon one must earnestly doubt the hwadu alone. Due to not resolving the mind properly or not knowing well the investigation method of hwadu, the hwadu is not taken up well. And so there are those who gain confidence through such mindfulness of hwadu or the chanting of hwadu.
However, the life of the investigation of hwadu lies in exciting the feeling of doubt. If one does not give rise to the feeling of doubt one cannot be said to be investigating the hwadu. Even though one continues to devote oneself to the hwadu by constantly chanting it and are without worldly thoughts, one definitely will not be able to conquer the hwadu by such methods. People who devote themselves to the mantic powers and the chanting or mindfulness of the hwadu without the feeling of doubt will often not give rise to mental resolution as they should.