Tozan traveled thousands of miles across China to study under Master Unmon only to receive "sixty blows" and the epitaph "Rice bag!" at their first meeting because, when asked mundane questions about his journey, he gave only mundane answers.
"Sixty blows" (literally "three tons of blows") is probably metaphorical, but one blow would have sufficed to deliver the message. The question is raised, in this the 15th koan of the Mumonkan, why perfectly normal answers called for a beating. Because they failed to demonstrate Zen awareness, of course. But the questions remain what that awareness with reference to his travels might be, and how he might have expressed it.
I won't even attempt to answer either of these questions, but will rather consider the reason Unmon could authoritatively deliver his blows. In his commentary, Mumon asks us if Tozan "should" have been beaten. "If you say he ought to be beaten," he writes, "trees and grasses and everything ought to be beaten." This is an insight ever much as important as Tozan's case.
If the unenlightened Tozan deserves a beating then everything in the Universe deserves a beating. Why? Because Tozan, unenlightened though he be, is perfect just as he is. All things are perfectly okay just as they are. If Tozan deserves a beating for his imagined failings, then so does everything else in the Universe, including Unmon.
This is the view from Dao. All is well. Every single thing is perfect just as it is. Whatever else it may be that Unmon 'understands' consequent to his own satori, this is fundamental. He has experienced the equality of all things. He has transcended the discriminating mind.
How then is it that he deigns to rain blows upon Tozan for his imperfection? For the same reason Tozan stands before him. Not-one is also One, but not-one is not amiss in its desire to realize that Oneness. Imperfection is also perfection, but, in realizing this, imperfection is perfected. To strive with imperfection outside the context of perfection, is to only deepen one's imperfection. Unmon's authority to rain blows upon Tozan is rooted in his appreciation of Tozan's perfection just as he is. Because he has seen this, he is able to assist him in his desire to realize the same.
But this is only half the equation. Unmon has the authority to strike Tozan because Tozan stands before him. Tozan stands before him because he has acknowledged Unmon's authority and has submitted himself to that authority. Were Unmon to strike some innocent in the street, this would serve to demonstrate that he had not realized the view from Dao and had no authority to strike anyone at all, standing before him or otherwise. Unmon can judge Tozan because Tozan has asked to be judged. Unmon, who has realized a non-discriminating mind, can helpfully discriminate; those who have not can only do so harmfully. Only when we have truly realized the equality of things, the universal acceptability of all things, are we able to helpfully discriminate between them.
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