Barter and Growth

In Smith's concept of Barter, what is exchanged is a surplus from each party, each of whom thereby gains in the process.  Barter could thus be interpreted as a special case of Communication, if only the concept of Gain that the latter analogously entails were adequately grounded.  But, such grounding is problematic in the absence of a sufficient principle of Growth, which is difficult to establish in a system in which the 'Self' is conceived as a fixed concept, whether on Empiricist or on Rationalist grounds, e. g. as 'Self-Preservation', or as a 'bundle of perceptions', or as 'Cogito'.  In contrast, given a principle of Growth, Communication, Barter, and, subsequently, according to Smith, an increase in general Wealth, thus has an adequate organic basis.