This character cannot be seen among the tortoise plastron, bone, or bronze inscription characters but from the Tenbun (Zhuàn Wén) seal script on. Certainly, it can be divided into a left and right part. It, however, would be too rash to jump to an A+B style mathematical explanation. Dr. Shirakawa summarizes: “The meaning is to realize an oath.”
Rather than a mere superficial interpretation like that of a 言 ‘kotoba: word’ that 成る ‘naru: realizes,’ one has to take the customs and religion of ancient China into consideration here. As was pointed out in the explanation of 信, the 口 of the lower part 言 is a vessel for putting in prayer writings. The meaning of the upper part with its four horizontal lines is hard to understand from the form of the Common Use Kanji. Its original form and meaning has to be understood in the context of the tattoo and ritual body painting culture. It shows the form of an instrument, a needle with a handle for tattooing. Already this part 言 only has the meaning of words of oath to the gods.
The part 成 shows the form of the ritual of completion performed after the making of a 戈 ‘hoko: halberd’ is finished, adding a decoration. This means that the left and right character parts have their origin in religion.