Original sentence: The middle class is the group of people generally considered to have average income, neither especially rich or especially poor
Edited sentence: Its usage has often been vague whether defined in terms of occupation, income, education or social status.Modern social theorists—and especially economists—have defined and re-defined the term "middle class" in order to serve their particular social or political ends.The definition by any author is often chosen for political connotations.The middle class is a class of people in the middle of a social hierarchy.Within capitalism, middle-class initially referred to the bourgeoisie; as distinct from the nobility, then with the further differentiation of classes as capitalist societies developed to the degree where the 'capitalist' became the new ruling class, the term came instead to be synonymous with petite bourgeoisie