In the oracle bone script, 古 is written , in the bronze script it is written . The character shi 十, ‘ten’, the “from ten mouths” in the Shuowen, is not the number ten, but is instead derived from the in the oracle character or the in the bronze character.
One can use the character’s tu 土 and wu 午 as examples: in the oracle bones, tu is , and in the bronze script, it is . The and represent pieces of earth, whose form later developed into ; they do not represent the numerical ten, ‘十’, in modern Chinese. The Chinese wu in the oracle script is , and in the bronze script. The bottom part of the character, or , represents a stone pestle, and is not the numerical ten. So the ‘十’ in ‘午’ and ‘土’ developed from or . Similarly, the ‘十’ in ‘古’ developed from or . The or in ‘古’ can be taken to represent a physical substance, therefore is an ideogrammic compound for ’something outside of the mouth’.
It’s difficult to understand what ’something outside of the mouth’ may mean, but if we look at similar characters in the Naxi script things become clearer. The Naxi , k’a33, is recorded in the Register of Naxi Pictographs as having the meaning “bitter, an object coming out of the mouth, ‘’ represents bitter flavour.” The oracle bone script and bronze script have precisely this original meaning: something bitter coming out of the mouth. This being the case, we can presume that the original meaning of gu 古 was in fact ku 苦, bitter. Gu is therefore a simple ideogram (指事字) and not an ideogrammic compound.
In order to provide further evidence for this theory, Fang uses the example of the Chinese gan 甘, which means sweet, the antonym of bitter. Gan is described in the Shuowen as “from ‘mouth’, holding one [thing]“. When we compare the character for gan 甘 in the oracle bone script, , with the Naxi pictograph , tɕʼi21, which means ’sweet’, we can see that the ‘one [thing]‘ that is being held in the mouth is a piece of food, being held in and not spat out, hence sweet – the character is a simple ideogram.
Many of the representations of oracle bone and bronze characters in this article are taken from Chinese etymology, a most excellent resource on the subject.