Who were the Barbarians in Matthew Arnold’s classification of English society?

In his seminal work Culture and Anarchy, the British critic Matthew Arnold classified the English aristocracy as the "Barbarians".1

Arnold characterized this group by their "lofty spirit," "serenity," and "distinguished manners". However, he also critiqued them for being largely inaccessible to new ideas. This classification was part of his broader social analysis, in which he contrasted the Barbarians with the "Philistines" (the commercial middle class) and the "Populace" (the working class). Arnold argued that none of these classes alone possessed the "best self" required to guide the nation, suggesting instead that the state should serve as the repository for collective cultural perfection.21