One major motif in Potter's writing is the concept of betrayal, and this takes many forms in his plays. Sometimes it is personal ("Stand Up, Nigel Barton"), political ("Traitor"; "Cold Lazarus") and other times it is sexual ("A Beast With Two Backs"; "Brimstone and Treacle"). In "Potter on Potter", published as part of Faber and Faber's series on auteurs, Potter told editor Graham Fuller that all forms of betrayal presented in literature are essentially religious and based on "the old, old story"; this is evoked in a number of works, from the use of popular songs in "Pennies from Heaven" to Potter's gnostic retelling of Jesus' final days in "Son of Man".