In the community where Jonas lives and in which The Giver is set, decisions were made many years previously to move to a culture and lifestyle of Sameness. However, the elders recognized that there could be situations in the future in which it would be important that someone have knowledge of how things used to be (before the community achieved Sameness), of how events could affect actions or people within the community. The Receiver of Memories assignment was created to allow one person to retain that store of information, to which the elders could appeal when the situation demanded. Jonas was assigned the position of Receiver of Memories in recognition of his special gifts, regardless of his reservations.
But why can't everyone have the memories? I think it would seem a little easier if the memories were shared. You and I wouldn't have to bear so much by ourselves, if everyone took a part."
The Giver sighed. "You're right," he said, "But then everyone would be burdened and pained. They don't want that. And that's the real reason The Receiver is so vital to them, and so honored. They selected me – and you – to lift that burden from themselves.
First of all, Jonas did not assigned in the ceremony, he was selected to be the Receiver of Memory. It is one of the most honorful assignments in the community and it is very important. Only The Receiver Of Memory can know about the past and the real world in the community. Also The Giver knows them but he just transmits the memories. Jonas has an unusual job because he is the only one to feel pain in his trainings. He will be the only one to be experienced about the real world.