Matthew Arnold was an accomplished poet and literary critic.  His main influence was on establishing universal aesthetic standards in criticism of art.  He said the role of critic is:

a disinterested endeavor to learn and propagate the best that is known and thought in the world, and thus to establish a current of fresh and true ideals.

Perhaps his most important work is Culture and Anarchy: An Essay in Political and Social Criticism (1869). He classifies society thusly:

1. Barbarians (the aristocracy)
2. Philistines (the middle class)
3. Populace (the lower class)

So says Enotes:

While Arnold praised the aristocracy for their refined manners and social assurance, he also condemned them for their conservatism. “Philistines” Arnold considered hopelessly uncouth though innovative and energetic. The lower class he dismissed as an ineffectual, inchoate mass. Arnold argued that as the middle class gradually assumed control of English politics, they must be transformed from their unpolished state into a sensitive, sophisticated, intellectual community.