When The Man comes down with a fever, he has some crazy dreams. He also recounts a near-visionary childhood memory of men burning snakes. The memory articulates a lot of the complexities of evil – and of fighting against evil – that are present in the book.
Standing at the edge of a winter field among rough men. The boy's age. A little older. Watching while they opened up the rocky hillside ground with pick and mattock and brought to light a great bolus of serpents perhaps a hundred in number. Collected there for a common warmth. The dull tubes of them beginning to move sluggishly in the cold hard light. Like the bowels of some great beast exposed to the day. The men poured gasoline on them and burned them alive, having no remedy for evil but only for the image of it as they conceived it to be. The burning snakes twisted horribly and some crawled burning across the floor of the grotto to illuminate its darker recesses. As they were mute there were no screams of pain and the men watched them burn and writhe and blacken in just such silence themselves and they disbanded in silence in the winter dusk each with his own thoughts to go home to their suppers. (261.1)
This is an instance of human beings confronting evil and failing to destroy it (although they think they have). One of our favorite sentences in the novel is, "The men poured gasoline on them and burned them alive, having no remedy for evil but only for the image of it as they conceived it to be." Basically, McCarthy is saying that the men here only destroy the image of evil, not the actual thing. Which is perfect for the novel, right? We might think we're civilized and that we've destroyed the great mass of serpents within us, but, as The Road argues, it's still there lurking beneath the surface.
Also, notice that The Man encounters the "bolus of serpents" when he's not much older than The Boy. There's a parallel exposure to evil here: The Man when the "rough men" open the hillside to burn the serpents and The Boy now as they're traveling the road.