Theodora was first performed on 16 March 1750 at the Theatre Royal in Covent Garden, based on a libretto by Thomas Morell. The oratorio is set in Antioch, Syria, during the persecution of Christians in the final years of the Roman Empire, under the reign of Diocletian (284). Theodora, a Christian of noble origin, refused to accept the invitation of Valens, the Roman governor, to celebrate the emperor following the pagan tradition. Furious, Valens condemns her to the dun-geon and death. Didymus, a Roman officer converted to Christianity by Theodora and in love with her, tries to take her place in the dungeon by disguising himself. But the ruse is discovered. Didymus is in turn sen-tenced to death. Theodora decides to join him in prison to face death with the one she loves. According to the librettist, Handel, then 65, considered Theodora his favourite oratorio. The dramatic power of expression in the composition, usually in minor key, is admirable. As in Theodora’s despair in the aria ‘With darkeness deep as my woe, hide me, ye shades of night’, introduced by the famous largo, or in Irene’s appealing aria ‘Defend her, Heaven, let angels spread’.