In the book, "The Giver", what is the significance of the ceremonies?

The ceremonies mark the passage of time in the utopian society in which Jonas lives. They occur every December and take the place of birthdays. For children up to the age of twelve, these ceremonies are a sign of their maturity, and they bring new responsibilities and/or the loss of certain objects. Although these phases of life are normally highly-emotional and individually celebrated in our society, they are rigidly controlled as natural progressions in life.