why is it necessary for there to be a receiver? (chapter 9-11)

After Jonas arrives for his first training session, he learns that he is to receive the memories of his entire society so that the other members of his community do not have to bear them. Someone has to remember, and someone has to be able to counsel the decision making process in the community.

The many books in the Annex also represent the stored knowledge and memories of humanity, which apparently are kept just in case they will be needed. This last set of remnants of memory and a different way in the civilization provide a sense of hope that there may still be some small chance of restoring what was lost when the society chose stultifying, riskless Sameness.