Throughout A Day No Pigs Would Die, Robert is presented with trials that test and toughen his character, gradually bringing about his transition into manhood. When Robert is forced to allow his best friend to be butchered so that the family can eat, it shows that he has accepted that some things in life are inevitable and that being a man is all about doing what has to be done.
Robert Peck is not like the other boys that he goes to school with in Learning, Vermont. He is the son of an impoverished farmer and a Shaker, both of which create a sense of isolation in Robert. He does not deal well with being different in the beginning of the book, as shown when he runs away from his trouble at school and does everything he can to avoid going back. Later in the book when Robert becomes a man, he accepts his position in life and discovers that Pinky has not been his only friend.
All of the major characters in A Day No Pigs Would Die are people who, though easily seen within certain categories (e.g. farmer, Shaker, adolescent), assert their individuality by displaying original ideas and attitudes toward life. Haven, for example, is a devout Shaker, but when his son asks him if he believes in all of the Shaker Laws, he only replies, "Most." In several situations he goes against Shaker ways to make his own decisions. Mrs. Peck exhibits this same characteristic. When Aunt Carrie is fretting over the adultery of the Widow Bascom, Mrs. Peck gives her approval for the way the widow carries on with life after her husband dies.
A Day No Pigs Would Die is all about the way that its characters react to the traumatic events that they experience. One of the things that Haven tries to teach his son is that there is nothing that they can do about these tragedies except carry on. When Haven dies in the end of the book, his son and family show that they have learned this lesson thoroughly by carrying on with life as if it were any other day.
A Day No Pigs Would Die is full of episodes where things die. What readers are meant to understand is that these deaths are necessary for the continuation of life. When Robert and Pinky watch the hawk swoop down and kill a Rabbit, they feel sympathy for the rabbit, but at the same time, they have an even greater appreciation for the majesty of the hawk. The same idea is shown more clearly when Robert is forced to sacrifice Pinky so that the family will have enough food to survive the winter.
Everything that happens in A Day No Pigs Would Die is a part of Robert's education. He has a formal education at school, the constant teachings of Haven, and the lesson that he learns from his own experiences. Though all three are valuable, the latter is clearly the most important in Robert's evolution. Only when his education is completed does Robert become a man and assume the responsibilities of the family.
More than anything else, the characters of A Day No Pigs Would Die strive to create and maintain order. When Haven dies, for example, Robert and the rest of the Peck family deal with it by trying to go about their days as if nothing special has happened. When Robert discovers his father, he doesn't even immediately run into the house screaming but calmly finishes his chores before going inside to break the news. It is when the daily routine of the Pecks' lives are broken that trouble is created. When Pinky does not regularly come into heat, it is the final straw that leads to her being butchered.
At several points of A Day No Pigs Would Die, Robert daydreams about thinks that he wishes that he owned. There is the bicycle for which he asked when he was younger, the store-bought coat, and his desire to go to a baseball game. As the story goes on and Robert matures, these desires disappear, symbolizing his acceptance of his position in life.
After Haven Peck dies, Robert finds himself staring at his butchering tools in the tackroom. The handles are dark brown with old age except for the places where Haven's hands had touched them, which are a rich golden color. This is symbolic of the effect of Haven's hard work on the family and especially on Robert. Just as the tools are gilded by his father's touch, Robert is gilded by the love and experience that Haven lavishes on his son.
In the beginning of A Day No Pigs Would Die, Haven scolds his son for skipping school because he wants his son to be able to walk into the bank in Learning one day and write his name. Later he also explains to his son that he is not allowed to vote because he is illiterate. He explains that people just see the X that he uses for his signature and completely ignore the type of man that he is. After Haven dies, while rummaging through the tackroom, Robert comes across a piece of paper on which Haven had been practicing his signature. One of the "Haven Pecks" is almost perfect. This symbolizes that though Haven dies, he had accomplished his goal of making Robert a man.