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.