What was the author's purpose of writing The Giver?

In the book the Giver by Louis Lowry, the purpose was to demonstrate to the reader the importance and significance of memory to human life. Her inspiration came when she visited her aging father who has lost most of his long term memory. She soon came to realized that without memory, there is no pain because you cannot recall those painful experiences which were a part of your life.

All your past experiences painful or not constitute your life and if you cannot remember them and they are completely forgotten, you may as well be dead.