Jonson told Drummond that he had once begun to write a comedy based on the Amphitryo of Plautus. He abandoned it because, as he said, ‘he could never find two so like others that he could persuade the spectators they were one’ (Conv. 420–3). It is a revealing comment. The plot of the Latin play hinges on mistaken identity in a doubled form. There is the real Amphitryo, Alcmena's husband, and there is the god who has temporarily assumed his mortal shape. Simultaneously, a real slave called Sosia confronts himself as impersonated by Mercury. Plautus had probably not had to worry about persuading the spectators that ‘they were one’. The Roman actors of his time are likely to have worn masks. Indeed, it is clear from the Prologue to the Amphitryo that Plautus was far more concerned lest his audience fail to distinguish between the true Sosia and the false, the real Amphitryo and the adulterous god, and so lose its way in the plot, than he was about any difficulty in believing that they could be mistaken for each other. This is why he explains so carefully that the actor who plays the false Sosia will be wearing a distinguishing feather in his hat, and the false Amphitryo a gold tassel visible to the spectators but not to the other characters in the play.

Elizabethan actors did not, of course, wear masks. They performed, moreover, in close proximity to the audience, usually in full daylight.