This radical was developed from a circle with a central dot as the image of the sun. As you can hardly draw circles or dots with a brush, it became the current rectangular shape.
In the explanations this radical is also used as a sitting person. (Further radicals with „person“ are: sitting cross-legged 夂, lying , kneeling ⺈, skilled 才, bending マ,卩, slumped 㔾 or husband 夫)
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