One of the coolest aspects of Light in August is the way the mood of the novel shifts constantly between light comedy and dark drama. There's a big difference in tone between the quicker-paced, comic mood of Byron's life at the mill or his odd love story with Lena, and the tragic tale of Joe Christmas's life. The lighter portions of the novel tend to feature more dialogue and great one-liners:
"I reckon that being good is about the easiest thing in the world for a lazy man." (2.18)
In contrast, many of Christmas's chapters focus more on descriptive detail and thoughts:
Then it seemed to him, sitting on the cot in the dark room, that he was hearing a myriad sounds of no greater volume – voices, murmurs, whispers: of trees, darkness, earth; people: his own voice; other voices evocative of names and times and places – which he had been conscious of all his life without knowing it, which were his life, thinking […] God loves me too. (5.7)
These differences in tone keep the novel from getting boring, which is always cool. But they also turn the book into a tragicomic hybrid that puts southern American humor in contact with the horrific legacies of slavery and racism in America.