Upper Class: Lives on the work of others, through investments, ownership of land and corporations, or even slavery.
Upper-Middle Class: Controls their own means of production (like an author, or a small business owner), with enough extra money for savings, education, and charitable donations.
Middle Class: Able to survive without help through their own work, with enough extra money for investments, savings, education, entrepreneurship, and charitable donations.
Lower-Middle Class: Able to survive without help through their own work, but unable to save up or invest in entrepreneurship or education; unable to give to charity.
Lower Class: Unable to survive without help.
Slave Class: Treated as property.
Sometimes people talk about the "American Dream" being someone from the lower classes who rises to the upper class. That's not my dream. My dream is for every American to be in the middle class, and to have the opportunity to rise to the upper-middle class, if that's what they want to do. I think the upper class, lower-middle class, lower class, and slave class will not exist in Zion.