What is a common theme found in many works of Eugene O'Neill?

Eugene O'Neill often explored the theme of tragic struggle with identity in his works. Many of his characters grapple with their inner demons and the conflicts between their personal desires and societal expectations. This struggle is highlighted in plays such as "Long Day's Journey Into Night," where family members battle with deep-seated pain and thwarted ambitions. O'Neill's use of complex characterizations often reveals how the search for self and reconciliation with one's past can lead to profound suffering, thus emphasizing this tragic element in the quest for identity.

While other themes, such as love or social issues, are present in his works, they often intersect with the individuals' identities and personal tragedies, reinforcing the central theme of identity as a poignant struggle throughout O'Neill's oeuvre.