Armstrong begins addressing the issue of identity with the title of the book. "Sounder" is the only name that ever appears throughout the entire text, and it is ironic that the only being with a name is not human, but a dog. Armstrong suggests that Sounder has more of an identity than the rest of the people in the book, and it is precisely these unnamed characters that gave the dog his name in the first place—to them, "Sounder" means something. To the rest of the world, the boy and his family mean nothing.
The defining characteristic of the boy's family is that it is a poor one, and when the boy walks around the town he constantly looks in the homes of important people, sometimes even those homes in which his mother works to earn money. All of these people have identity and importance. Even people such as the jail guard have identities, since he has a title based on his profession, despite the fact that Armstrong does not give him a name. The boy has no such title, nor does his mother. His father has no name either, yet he earns the title of convict or thief—titles that relegate him to the lowest of the low, regardless of what and whom he really is. The lack of identity underscores the intense hardships involved in the lives of black sharecroppers, and how difficult it is for them to achieve, even if only in the achievement of a name.
Even though the boy is referred to as "the boy" despite growing up significantly, it is clear that he has aged emotionally beyond his years. Life was difficult for him before his father was taken away, but, until that time, at least he had some claim to being a child. He looked up to his father and waited anxiously for the time when he would be old enough to have some of the same responsibilities. When the boy's father is taken away, he is suddenly thrust from his childhood into a position where he must tend his younger siblings, watch over his mother, and labor for food. At one point in the novel, the boy reflects that he does not know how old he is, but he knows he has lived for a long, long time. He is weary and old in spirit, even while young in age.
The single comforting source in the boy's life is the Bible, particularly the stories in which he can find parallels to his life. The boy dreams of floods that unite the town in water, thinks of David and Goliath, and thinks of the way characters in the Bible are able to confront and prevail over their fears. He yearns for respite from the real world and notices the differences between stories in the Bible and stories in the newspaper. While he knows that the real world is not as fair and wonderful as the Biblical world, he still reads the Bible for hope, particularly when faced with the challenge of seeking his father. The fact that many characters in the Bible went on long journeys and found those things for which they were looking, serves as motivation for the boy in his search for his father.
The book resonates with the theme of who and what is left behind. First, both Sounder and the father leave behind the boy and his family. The boy's father left behind Sounder as well. Being left behind also carries along with it new responsibilities: the boy is left behind to care for his siblings, while his mother is left behind to earn money for the family and tend to all of the shelter, food, and clothing needs. When the boy comes to visit his father in jail, his father in a sense leaves him behind again, by requesting that the boy never come back. Later in the text the boy finds a book that was left behind, and then he leaves his own family behind to live and study with the teacher. Sounder and his father leave them all behind again when they die. Armstrong illustrates these life-changing movements, tracing and crossing the lines between together and apart.
Some of the novel's most poignant moments come when the boy is describing his loneliness. He develops something he calls "night loneliness," which is the acute awareness of solitude. This becomes worse after his father and Sounder leave because he can no longer associate nighttime with their hunting escapades. Sometimes the boy is so lonely he does not know what to do: Armstrong describes the loneliness as a near-paralysis that is difficult to overcome. Even though the family lives together in a small cabin, they all feel alone, which only underscores how lonely the boy's father must feel in the jail, how lonely the boy's mother must feel without a husband, and how lonely Sounder must feel without a family. The family's position and status ostracizes them as well, making them feel lonely and friendless as a unit.
Despite the hardships that seem to be unceasing, characters in this novel somehow never lose a sense of optimism. The boy looks for Sounder every day and holds out hope for the dog's return even after weeks go by. The same is true for the boy's father, and the boy embarks on long treks throughout the county to find him. Also, the boy's determination to learn to read is not diminished by sadness or pessimism. The boy's mother also maintains a sense of hope and never allows any feelings of desperation to show or to overwhelm her. They pursue life doggedly, always enduring and always hoping.
As much as the boy strives to find Sounder or his father, he strives as much if not more to learn to read. It is implied that the reason he does this is to better himself, because he knows that his chances are better in the future if he is literate. He also reads as a means of escaping his life and immersing himself in beautiful and often comforting stories. Finding a book in a trash can eventually opens up the opportunity for the boy to study with the teacher, changing his life forever, improving it exponentially. Armstrong uses the book to represent the road to improvement.
After the boy's father is arrested and Sounder is gone, the hunting bag is a reminder of their absence. Simply looking at the bag makes the boy lonely, and it makes him long for the days when his father and Sounder used to go hunting, even if they used to come back empty-handed. The empty bag hanging on the post represents loss and emptiness. Once Sounder and his father return, the bag symbolizes what they used to be able to do and what they used to have. When Sounder and his father die, the bag is a reminder of them both; while at the same time, the bag underscores the fact that unlike his father, the boy does not hunt, but instead is concentrating on education.
The boy is injured while staring at a group of convicts. He is holding onto a fence, and the guard smashes his fingers with a piece of iron. The fence is symbolic of the distance between the boy and his father, and it is also symbolic of the many gaps that the boy cannot seem to transcend—he cannot get close to his father, he cannot quite learn how to read, and he cannot quell the loneliness that torments him. The fence is representative of the fact that the boy is in many ways an outsider.