The central ideas would be that the author has proved his point that no one in this world would be born and reached the top of a success without spending an enormous time of practice which would be -- 10,000 hours.... His other central idea would be that according to him, as the psychologists look at the careers of the gifted, innate talent plays a smaller role but rule preparation or practice plays a bigger role to succeed.
The Giver tells Jonas that memories are meant to be shared, saying, "The worst part of holding the memories is not the pain. It's the loneliness of it" (154). Imagine how lonely it would be to never be able to share your memories with another. Much of our joy in memory lies in the sharing of it.