As you recall, the question of the distribution and utilisation of the surplus is a key issue in classical Political Economy, intimately tied to reproduction and growth and underpinning the definitions of productive and unproductive labour. Smith provides the most generalised concept of the surplus, essentially holding that all profit-making activities contribute to it. This suggests that accounting questions (e.g. the measurement of profit) play an important role in the interpretation and use of the theory. The background material contains some striking findings with regard to the effect of incorporating environmental costs (damage to natural capital) into the measurement of profitability (there is an executive summary if you don't want to read the whole thing!) What are the implications for the way we think about and evaluate classical theory (and modern theory for that matter)? What implications does it have for how we measure and interpret growth, and how we should do so? Have we been on the wrong track