Prof. Lee makes many good points in his very lucid exposition; however, i harbor serious doubts that the definition of a global middle class from the OECD that ranges from $3,650 to $36,500 is either useful for policy or very meaningful. It is way too broad a range and also isn't calibrated by country. After all, the middle class should be seen in the context of the distribution of income in individual countries. Hence other definitions, such a 50-150% of the mean income per capita may be a better measure for policy as well as illustrative purposes.