One of the themes of The Story of Edgar Sawtelle is the use of different forms of language to communicate. Edgar is born mute, so he can only communicate with his parents and the dogs around him using a private form of sign language. However, he is able to make himself understood, and the dogs around him understand him perfectly. After his father mysteriously dies, Edgar can even communicate his suspicions to his uncle, Claude, in a way that is perfectly understandable. It is actually the verbal characters who are more confusing; for example, Edgar does not understand the disagreements that erupt between his father and his uncle. The author writes:
Though the details differed each time, Edgar got the idea that Claude and his father had slipped without their knowing it into some irresistible rhythm of taunt and reply whose references were too subtle or too private to decipher. Whatever the dynamic, it wasn't Claude's only aversion. Group discussions left him looking bored or trapped. (122)
Interestingly, Edgar, who uses his own signs combined with a form of American Sign Language, can communicate more clearly than characters such as Claude, who are verbal.
Another theme in the book is the wisdom of animals and their sixth sense. While Edgar struggles to understand his parents and, later, his uncle and the vet who works with his dogs, the animals around him seem to understand everything. For example, Edgar's dog, Almondine, senses Edgar's arrival before he is even born. The author writes of the dog, "Eventually, she understood the house was keeping a secret from her" (47). She knows that Edgar is on his way and that she will have a special relationship with him before he is born. However, the human characters in the novel do not have the insight and wisdom that the dogs do.