Moral Philosophy: The idea that it would be good if all in society were equal was pretty much completely foreign to Mediæval Europeans. Things, were instead, supposed to be equitable—which meant treating people who were unequal in rank, virtue, and contribution to society unequally. Society could not function well without this equitable inequality. The people who overthrew this were, I think, Rousseau and Turgot. Did they do so single-handed? (Or, rather, double-handed.) Or are they litmus tests for a shift in hearts and minds that came from elsewhere? I don’t know. Whichever is the case, however, Alfani and Frigeni have the goods:

Guido Alfani &Roberta Frigeni (2016): Inequality (Un)perceived: The Emergence of a Discourse on Economic Inequality from the Middle Ages to the Age of Revolution: ‘During the Middle Ages… aequalitas… cannot be separated from… aequitas (equity) and is also closely tied to that of civitas as a body… liberalitas/largitio (generosity), and of the vice avaritia (avarice) and vi tuous opposite, prudentia (prudence)…. After the [French] Revolution, however, aequalitas (égalité) boomed while aequitas declined…. the French Revolution spread a new use for the word and concept of equality across Europe… <researchgate.net/publication/311010407_…>