Maybe by "middle class" he meant the old classical economics definition of the word: The rich did not work, they owned land and collected rent or a share of crops. The Middle class owned factories and other businesses. They did work at running those businesses. The working class were employees. The poor were unemployed.

We have shifted the meaning of these titles. Now we call business owners rich and there is hardly a word to describe the real rich. It's actually a ploy by the real rich to hide just what "rich" means. This is why some people are freaked out by various pols calling for a 73% top tax rate on income above $10 million per year. Who makes more that $10 million per year? A few thousand people in the US and they own most of the wealth.