Dominant Hand aka Dominant Thought: if it talks like a duck, walks like a duck, looks like a duck, must be a duck
On the Other Hand? ¯\_(ツ)_/¯: could be a rabbit?
Our human mind can't do both at the same time! It has to take turns. Even if the taking turns is switching several times in a single second.
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So even the wisest of us will always have "blind-spots" for you can't look left and right at the same time. You can't do everything at once. Instead you must have faith in others, and the system, and so on. Yet even with faith in others and the system, the world will constantly fail from time to time, that is the nature of reality. ¯\_(ツ)_/¯
The hero's journey type stories (not all stories are hero's journeys) of a teenager hero becomming an adult is really at its core teach the reader / listeners one of life's great truths. This truth is one of introspection and a form of mysticism. A form of "mystery" solving which considers the path of movement toward and away from anything in our world
as not always a straight line,
but rather periods along the journey of striving, failing, and striving again…
a rising and falling of energies along the path. One must fail in order to later succeed and to understand a greater insight.
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This is why the Avatar had to be human in Korra and can't just be a light spirit. For the spirits are "fixed" immutable concepts that are abstracts in the Avatar world. They are able to change, but they are not able to change their core nature and thus they find it hard to incorporate their opposite concept, they find it hard to work in tandem with their opposite to provide neutralizing energy but also neutralizing energy can allow a "foundation" for other energys to build.
Thus for a new insight to occur, Aang has to fail, Aang had to forget, in order to allow Korra to experience, for Korra to remember not as in memory but instead to remember as in "to call to mind" and to be mindful and to see things with a new fresh perspective.
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Toph had to be a bad parent for she was awesome at dozens of other things and you can't be awesome at everything at once. EVEN IF YOU ARE TOPH!
Aang can be a loving parent but still not see everything at once, and be everything at once for that is the nature of being human. ¯\_(ツ)_/¯ We should not hold Aang to an impossible standard for that is a form of objectifying and treating him not as human but like he is some demigod or fetish object.