Why did Matthew Arnold consider ancient Greece modern in spirit?

Matthew Arnold considered ancient Greece "modern" in spirit because he defined the term "modern" not merely as "contemporary," but as a specific intellectual and emotional state.1

In his inaugural lecture as the Oxford Professor of Poetry, "On the Modern Element in Literature," Arnold argued that the "modern" spirit is characterized by a mind that contemplates the vast, complex spectacle of life and, in response, craves moral and intellectual "deliverance". He viewed the ancient Greeks as possessing this same spirit, as they faced their own intricate world with a similar need for clarity and understanding.1

By identifying this shared impulse, Arnold sought to position classical masterpieces as essential models for his own era—a time he described as suffering from "spiritual discomfort," "sick hurry," and "divided aims". He believed that the nobility and plainness found in Greek literature could serve as a vital medicine for the challenges of the 19th century.1