How did Sophocles structure a tragedy differently from Aeschylus’s connected trilogies?

Sophocles significantly altered the structure of Greek tragedy by moving away from the Aeschylean framework of the connected trilogy, in which three plays collectively explored a single narrative arc. Instead, Sophocles comprised the entire dramatic action within a single, self-contained play.12

His structural innovations included:

• Introduction of a Third Actor: By adding a third actor, Sophocles increased the number of characters and allowed for more complex, fluid interactions, which necessitated a more sophisticated dramatic structure than the two-actor model used by Aeschylus.21
• Reduced Choral Importance: While Aeschylus’s dramas were often centered on the chorus, Sophocles reduced the chorus to a more commentarial role, allowing the dialogue between actors to carry more of the play's meaning.34
• Concentrated Action: Sophoclean drama is characterized by great economy and concentration. He focused on a few powerful characters whose specific traits and choices lead them inevitably toward a tragic fate, creating a coherent and suspenseful narrative that functions independently of other works.14

Following Sophocles, the term "trilogy" evolved to simply refer to three separate plays by the same author presented at a festival, rather than a unified dramatic whole.1