As the devils explore Hell, Satan makes his way toward the gate out of Hell. This section of Book II begins the one extended allegory in Paradise Lost. An allegory is a literary work in which characters, plot, and action symbolize, in systematic fashion, ideas lying outside the work. While much of Paradise Lost deals with Christian ideas and theology, only in this section does Milton write in a true allegorical manner.
At the locked gate where he may exit Hell, Satan finds two guards: his daughter, Sin, and his grandson, Death. The way Sin and Death were created explains the nature of allegory. Sin was born when Satan, in Heaven, felt envy for Jesus. Sin sprang from Satan's head (symbolically his thoughts) just as Athena (wisdom) sprang from the head of Zeus. Death was born of the unnatural union between Satan and his daughter. Finally, adding to the general nastiness of the story, Death raped his own mother, Sin, creating the Cerberus-like hellhounds that gather around her waist.
The allegorical interpretation of this story is, in its simplest form, easy to follow. Satan's envy for Jesus was a sin, which becomes manifest in the character of his daughter, Sin. That is, the concept of sin in Satan's mind literally becomes Sin, a character. Sin, in conjunction with satanic evil, produces Death. Finally, Sin and Death together produce the hellhounds that will come to plague all mankind. The allegory here can be explored more deeply, but basically it explains, through characters and action, how sin and death entered the universe. Similarly, the fact that Sin opens the gate of Hell for Satan is also allegoric as is her inability to close it. Thus Satan, by leaving Hell, brings Sin and Death into the world.
