Hi, Hong,hong wrote: beh/bueh cannot be 必。It could be a baidu of 欲.In old chinese there are no要 but many yu 欲as verb。
I did consider 欲 as a possibility before, However, beh/bueh as the baidu for 欲 seems a bit of a far stretch, as we know 欲 does not have a b-/p-/m-/f- beginning. If anything, I would think that the baidu for 欲 would mostly likemy be 'ai' (want), but that one is most probably 愛.
That is why I thought 必 would be more likely, since (a) it also has a "b-" beginning and (b) it has the exact same meaning. I know it cannot be 卜 - that character is clearly "borrowed" for its sound, nothing more. But if your theory is that beh/bueh cannot possibly be 必, could you provide some insights on why that is the case? Does it mean that 必 only has one pronunciation, i.e. the wendu "pit"?