> there is no reason to believe that, in the absence of a centralizing force, the weights should standardize. In the absence of trade there would be no reason

> there is no reason to believe that, in the absence of a centralizing force, the weights should standardize. In the absence of trade there would be no reason for them to stabilise, but with trade there is every incentive for them to do so even over long distances and between people groups who don't know of each others existence.