 The script employs features of the epic theater associated with German playwright Bertolt Brecht, particularly with its realistic use of songs as well as the added anachronism of the actors, who performed the songs in modern dress, despite the fact that the play was set in the 17th century.There were seven songs and twenty-one scenes.The play's title comes from the name of one character's pet cat, supposed to be her familiar spirit, likely inspired by the supposed imp of one Elizabeth Clarke, a woman tried and executed for witchcraft in Essex in 1645.