Why did Yao Zi check the feather root?

Radical is the Chinese character classification initiated by Xu Shen in Shuo Wen Jie Zi in the Eastern Han Dynasty. Its principle is to take shape as the radical and set up 540 radicals.

When writing Kangxi Dictionary, I thought there were too many radicals to look up, so I added the method of using glyphs as radicals to reduce the number of radicals to 2 14, which is the popular radicals now.

The word "Yao" is light in shape and sound, so it should be based on "light"; The word "Guang" is reduced to less than 10, and the radical "Yu" of the word "Zhai" is used as the radical.