The most important thing is when Jonas got his Assignment as a receiver. The assignment is the most important event in the book because it changes everything he sees, thinks, says and feels. His whole life is changed because of this assignment.
The receiver is one of the highest assignments there is. You can almost do anything you want, like lie and ask questions which no one else can do. In the community, the job of receiver is there because they need someone to keep memories, so he can give advise to people in charge of the community on what to do in a situation. He than thinks back and see what happen the other time in the same situation, so they don't make wrong mistakes.
Jonas gets to know heaps about the community, that he and other people don't know, like there's more to do in life than just getting an assignment, like get a girlfriend listen to music and going on holidays.
He finds out what the community does, like how they release people, how they bring babes into the world and how they bring things into the community with out people know. This job brings him more understanding how to see colour and thinks differently through the memories.
On the other hand, he has memories of war, killing and loneness. This is real tough on the way he thinking off all those memories. This influences on what his says because he is aloud to ask questions, and he saw one of the twins getting released and he disagreed on what they did to the boy and to other people.
This assignment has a big impact on Jonas life. From listening to the rules to trying to escape from the community. Especially when he saw the release of the young twin boy and the boy's death at war. He tried to give some memories out to Fiona about how she has red hair and when Gabriel got a memory of a boat in the sea when he was crying in the bed when he knows that's wrong. Jonas is looking at everything different on what he sees, thinks, says and feels.