In the 17th century, especially in France, we had a class society. In the 18th century, clergy and nobility are not so important anymore, but we still have 3 estates. We now call them classes.
The 3 classes are;
Entrepreneurial class; Rich people, big houses, own factories and machines.
Middle class; Skilled people, office workers, shopkeepers, etc.
Working class; No property, No money.