How did Christoph Willibald Gluck combine recitative, arias, choruses, and pantomime into dramatic scenes?

Christoph Willibald Gluck revolutionized opera by rejecting the rigid, ornamental conventions of opera seria in favor of "simplicity, truth, and naturalness". To create cohesive dramatic scenes, he integrated various musical and theatrical elements into a unified architectural structure:12

• Integration of Forms: Gluck largely abandoned recitativo secco (unaccompanied recitative) in favor of recitativo accompagnato (orchestrally accompanied recitative), which allowed for smoother transitions between speech-like passages and arias.12
• Serving the Poetry: He ensured that music served the poetry and the narrative flow, avoiding the "useless superfluity of ornaments" that previously interrupted dramatic action.12
• Structural Synthesis: He welded recitative, aria, choruses, and pantomime together using a declamatory vocal style and expressive orchestral writing.2
• Role of Chorus and Dance: Influenced by Jean-Georges Noverre, Gluck elevated the chorus to participate directly in the drama and incorporated ballet as a meaningful component of the dance drama, rather than as an unconnected episode.12