Why did Matthew Arnold remove Empedocles on Etna from his 1853 poetry collection?

Matthew Arnold excluded his dramatic poem Empedocles on Etna from his 1853 poetry collection because he felt it lacked the necessary qualities of action and resolution.1

In the preface to that 1853 volume, Arnold explained that the poem was one in which the protagonist's suffering finds no vent in action, leaving the reader with a sense that there is "everything to be endured, nothing to be done". This decision reflected his evolving critical standards, which increasingly emphasized the classical virtues of unity, impersonality, universality, and architectonic power. Arnold believed that poetry should serve as a source of moral grandeur and consolation for an age of "spiritual discomfort," and he viewed the static, internal suffering depicted in Empedocles as inconsistent with these ideals.1