"The mind that does not understand is the Buddha. There is no other...." Ma Tsu
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For the record that is typical teaching. If you say you 'understand' something, that's not coming from the Buddha mind. Even 'understanding' is clinging.
Mind seeks and has to 'know' because it's part of filling the 'sack,' because ego hates to have an empty sack. It will only 'discard' if it thinks it can gain something better. So in Zen practice, the ego still has to be fooled into believing, whatever work you're doing, is for its benefit. Its part of emptying the sack and unraveling the tangles of its contents.
Ego is a normal function we're supposed to have. Seeking to aquire, if we didn't do this, we couldn't even progress to Buddha mind, at all. Or a mind which is unfettered, because how can anyone go through the progress of growth unless they reach the stage, of unfettering the mind, at all? And even ego is subject to change, but it only likes to change if somehow, it can feel some form of permanence within, that change, which, is difficult to do.
This is why koans were taught to zen students, because they 'slipped through' the ego and confused it. That's why they do work. Because ego can't cling to it, so it dissolves in its presence, because it can't 'resolve' what it hears in the koan.
The function to create memories is necessary, or else we wouldn't remember how to get home from work, or to brush teeth in the morning. Its when we begin to install programs, or cling to things and 'own' them, when ego can get in trouble. And knowledge would be one of those things, in its various forms.
Because we like to 'know,' we will do what we can, of the 'unknown' to fill in the blanks with 'something.' The problem isn't always what we learn and gain in knowledge, even if false or not, because we can recognize what we brought forth, in knowledge, and installed. But we have a hell of a time recognizing the unknown installations, the fillers in between. For example, a child might believe that storks deliver babies. The knowledge, is known cause mom told a cute story. However, other things the child may fill in, which are false and not be as easily retrievable. Such as what the stork wears, or that he delivers 100 baby boys and 80 baby girls per day. Little 'assumptions' when the mind wanders to fill in the gaps. So later, when asked where babies come from, and more is added onto the story, thought as something the child knows, in reality, he added to the story, made it his own. The whole thing was ficticious, and later when the truth comes out, he can discard it all. But say he forgot his addition, and believes that 100 baby boys and 80 baby girls are born each day, physically birthed by mothers, but 'forgot' he installed this strange belief by creation. Its a silly example, but it is one how ego will fill in the 'gaps' of knowledge with what it doesn't know, because it feels for survival purposes and functioning, it 'has' to know. This is why if you ask people their ideas on religion, spirituality, they will swear up and down something is true, via faith, but a huge amount of what people believe is actually handed down, borrowed knowledge. The difficulty with ego, in emptying the sack, is because it fears not knowing, and not understanding. To empty it, puts it in that position, a position of being vulnerable.
So when it is said, "The mind that does not understand is the Buddha," you have to step back for there is more written in that statement. Not only is zen not about grasping and 'understanding,' but the mind, automatically seeks to understand the statement! That's the beauty and the trick of the statement, so many miss. Like some will read that and think they've 'got it.' However, you dont, because like it says "The mind that does not understand is the Buddha." So if you think you 'understand' the sentence, you're not using the Buddha mind, to read it.
The point of zen, its beauty, is to unravel what you 'know.' This is why it works. Its not about learning 'more' only to be grafted into what you have been taught, to acquire. Its a system of disassembling all that you know. Stripping all down so their is nothing left, to cling to.