Scholarly consensus denies a real connection between ancient tragedy and early opera because music historians have measured early operas against an idealised conception of Attic tragedy. However, the pioneers of opera were seeking to revive a Euripidean style of musical tragedy as it was performed in the ‘decadent’ theatres of the Hellenistic era. Euripides's tragedies established conventional relationships between musical expression and the representation of the passions. Baroque opera is seen as a strongly complex reading of a set of Euripidean tragedies that enjoyed favour in the Hellenistic era but fell from critical grace in the nineteenth century. These plays hold the key to opera's tragic pretensions; the esteem they long enjoyed should prompt us to reconsider the spirit of tragedy and the nature of catharsis.