"Release" is a word used frequently throughout Lowry's The Giver, but children like Jonas are not quite sure what it means because the word is ambiguous at best. Jonas hears about release when working in the House of the Old, when a pilot flies over the community without permission, and when learning about Rosemary, the failed Receiver-in-training before him. When Jonas sees his father "release" a baby, he finally understands what everything else means. It's a traumatic experience to find out about death when he's been sheltered from it his whole life. Then, to discover that such a caring man like his father participates in killing babies at the same time as he discovers death is overwhelming. Lowry describes Jonas's reaction to his father killing one of the twins in chapter 19 as follows:
"Jonas felt a ripping sensation inside himself, the feeling of terrible pain clawing its way forward to emerge in a cry" (151).
There are a few things that shocked Jonas about this.
First of all, he couldn't believe that his father was just killing a baby. It seemed terrible to him since he had experienced memories of death.
Second, he could not believe that his dad was being so casual about it.
Third, he is shocked that his father lied to him and he wonders how many other people are lying as well.
All of these things shocked Jonas so much that he could not handle it anymore and decided that something had to be done to change the community.
What shocked jonas so much is that he couldn't believe his own father is creating a child death and he act so normal. It makes jonas feel unsafe and angry in some way because he can feel the pain.