Making your own decisions and doing whatever you want could cause unbalance and upset the community, so you have to follow certain rules and things are decided/chosen for you.
"Jonas was surprised. There was no way, really, to know in advance. It was a secret selection, made by the leaders of the community, the Committee of Elders, who took the responsibility so seriously that there were never even any jokes made about assignments." (Lowry 15).
Having your own personal thoughts and differences are discouraged and looked down upon.
"He paused. He knew he had to tell it all, that it was not only all right but necessary to tell all of a dream." (45).
"But there were few exceptions: Jonas himself, and a female Five who he had noticed had the different, lighter eyes. No one mentioned such things; it was not a rule, but was considered rude to call attention to things that were unsettling or different abilities individuals." (26).
Life is full of surprises and unusual things. Always be ready for the unexpected.
"Such a selection is very, very rare," the Chief Elder told the audience." (60).
"But at the same time he was filled with fear. He did not know what his selection meant. He did not know what he was to become. Or what would become of him." (64).
Being different/unusual is not always a bad thing, for example you can gain more knowledge and experience more than others.
"Finally he spoke. Beginning today, this moment, at least to me, you are the Receiver." (75).
"Now he became aware of an entirely new sensation: pinpricks? No, because they were soft and without pain. Tiny, cold, feather like feelings peppered his body and face. He put out his tongue again, and caught one of the dots of cold upon it. It disappeared from his awareness instantly; but he caught another, and another. The sensation made him smile. (80 & 81).