A five-year old John Christmas sneaks into the dietitian's room at his orphanage to eat some of her delicious-tasting toothpaste. He hears someone coming, and so he hides behind a curtain in the corner of the room. It is the dietitian and one of the interns from the hospital having a tryst. While Christmas waits for them to leave so that he can escape, he eats so much toothpaste that he makes himself sick. When he vomits, the dietitian, Miss Atkins, discovers him. Because she is so afraid of being caught, she begins to hate him and the threat he represents to her. Miss Atkins lives in a state of total anxiety for the next few days, believing that Christmas not only understood what he witnessed, but that he is intentionally delaying telling on her to punish her even more. She tries to bribe him to keep him quiet, but he is waiting for her to punish him for eating her toothpaste, so he does not understand and does not accept. She believes that this means he insists on telling on her. Miss Atkins approaches the orphanage's janitor, whom she has noticed watching Christmas with a deep hatred, to see if he will verify her belief that Christmas is part black. He does, but he will do nothing about it.
The next day Christmas and the janitor are both missing. They find them three days later, when the janitor tries to have Christmas put in a different orphanage where no one will know he is part black. While they are gone the dietitian tells the matron the reason for their disappearance, knowing that once Christmas is returned he will be placed in a home rather than be transferred to the black orphanage.
When the janitor takes Christmas away, the young boy passively accepts everything that happens. At first he does not know who has him, but when the janitor speaks he immediately recognizes him as the man who has been watching him obsessively ever since he can remember. They take a train to another orphanage, which Christmas again accepts without much wonder. Soon enough, the police come and get him to take him back. After his return, Christmas is taken to the matron's office, where there is a hard-looking man waiting to adopt him. This man, McEachern, takes Christmas home with him after inspecting him.
The next chapter opens with McEachern trying to teach Christmas, now eight years old, his catechism, but Christmas sits stubbornly, refusing to learn. McEachern takes Christmas to the stable, where he beats him and then gives him another hour to learn the catechism, but Christmas doesn't even try. Christmas, having had nothing to eat all morning, eventually faints, and does not wake up until later in the day. When McEachern finally leaves in the evening to go to church, Mrs. McEachern brings Christmas a tray of food. Christmas turns the tray over on the floor while Mrs. McEachern watches, and only after she is gone does he kneel down and eat the food off the floor.
At fourteen, Christmas goes with five friends to sleep with a black prostitute in a shed. When it is Christmas's turn he enters the shed, but the smell of the woman oppresses him, and he starts to kick and beat her viciously. When she starts to scream his friends run in and try to pull him off her, but he ends up fighting them just as brutally. They eventually run away from him, and he returns home to receive his usual beating from McEachern.
When Christmas is eighteen, McEachern finds a new suit hidden away, and then notices that Christmas's heifer is missing. McEachern gave the cow to Christmas to teach him the responsibility of ownership, but he realizes that as Christmas's property, it was his right to sell it. He is, however, disgusted that Christmas sold it to buy a new suit, which according to McEachern can only be used for lechery, and so he beats him.
From the time of Christmas's adoption Mrs. McEachern always tries to treat him well, but Christmas is so unused to kindness that he does not trust or understand it, instead finding it disconcerting. When she tries to defend Christmas to McEachern, he finds that it takes away the impersonal quality of the beating that makes it bearable, and so he resents all her kindnesses. He expects and is used to hard work and physical punishment and so accepts them, but he despises the unpredictability of Mrs. McEachern's kindness.
Chapters six and seven of Light In August go back in time to tell the story of Joe Christmas's childhood. In doing so, Faulkner continues to complicate the book's understanding of the possibility of truly knowing a human being's character. Until this section, Joe Christmas has been positioned as a deeply enigmatic character, seen only through the eyes of the townspeople. These two chapters give the reader a much closer and more personal view of Christmas, and yet even this knowledge does not make him any more understandable.
The two factors of his character that emerge most in these chapters are his hatred of women and anything feminine, and his obsession with his belief that he is black. In the first scene the narrator presents of Christmas's childhood, sexual intercourse and vomiting are closely tied. This link will reemerge later in the novel, but it is also significant that Christmas is surrounded by the "womansmell" of Miss Atkins's cloths when he becomes ill. For years afterwards, he continues to associate the dietitian and her femininity with a profound sickness.
Christmas's misunderstanding of Mrs. McEachern's attempted kindness also underscores his misogyny. He refuses to accept food from her, and he finds her attempts to placate Mr. McEachern only make his punishments harder to bear. When he first arrives at the McEacherns' farm, he is utterly confused by Mrs. McEachern's kindnesses, imagining that every nice thing she does must soon be followed by something unpleasant. He finds the behavior of women too unpredictable, and impossible to respond to with the stubborn strength that he employs with McEachern.
The scene with the prostitute highlights both Christmas's hatred of women and his obsession with his perceived blackness. When Christmas enters the shed to have intercourse with the prostitute, he is overwhelmed by the smell of the "womanshenegro." It is simultaneously her gender, her sexuality and her race that fill him with the urge to beat her-which he does, and yet even he cannot truly say why, thus underscoring the final impossibility of truly understanding any character in Light In August.
Christmas is clearly obsessed with his race-an especially striking fact given that he does not actually have any evidence of his background. Other children in the orphanage use racial slurs against him, yet of the adults only the janitor and the dietitian suspect that he is not white; the McEacherns have no idea. The fact that Christmas considers telling Mrs. McEachern what he considers the secret of his true race is surprising, for he has no rational reason to believe it is true.