The article simplifies complex economic concepts about money and exchange rates. It focuses on the real economy and the absolute level of prices. The authors use the classical dichotomy to analyze these aspects. They suggest using a general price level as a unit of analysis, like the GDP deflator or consumer price index. When it comes to international trade, they distinguish between tradable and nontradable goods. Tradable goods have prices set by the world market, while nontradables are services like transportation or food. It's best to use general price indexes rather than trying to directly measure nontradable prices.