What shocked Jonas when he viewed his father "releasing" one of the newborn twins?
In The Giver (Lowry), as Jonas watches his father release one of the newborn twins, he finally comes to understand what release is, and the horror of this, seeing a newborn put to death by his own father, disposed of like trash, makes him feel "a ripping sensation inside himself, the feeling of a terrible pain clawing its way forward to emerge in a cry" (151). Up until this point, Jonas had believed that those released went somewhere else, to live out their lives peacefully. He understands now that Rosemary, the previous Receiver, had committed suicide, rather than live with the memories she had been given. He sees that all of the elderly who had been "sent off" with such charming ceremonies had been sent to death. He realizes that the punishment for breaking the rules can be a death sentence. We can almost see all the wheels turning in his brain as he grapples with this new understanding and how it fits in with his prior understanding of release. This shock and horror are a pivotal point for Jonas, who cannot bear the thought of returning home to his father, who is an executioner. It is after this "viewing" that Jonas understands he must leave the community, so that the community will be forced to regain memory and feelings. This is going to be a struggle for them, but it is the only way they can become fully human again.
Throughout the majority of the novel, Jonas did not fully understand the meaning of the term "release." In Chapter 19, the Giver makes Jonas watch footage of an infant twin being released by Jonas' father. Jonas is shocked and disturbed as he watches his father inject a lethal substance into the newborn's scalp, which immediately kills the child. Jonas' father then places the dead infant into a small carton for disposal. Upon seeing the video of the newborn's death, Jonas is disgusted, confused, and angry. He had no idea that the term, "release," was a euphemism for death. Jonas begins to cry and refuses to go home after witnessing his father kill the infant. Jonas feels betrayed by both his community and family. The Giver then explains to Jonas that even the elderly are lethally injected during their release ceremonies. The fact that individuals are killed when they are released permanently changes Jonas' perspective on his community and family.