Jean-Jacques Rousseau

The growth of a child is divided into three sections, first to the age of about 12, when calculating and complex thinking is not possible, and children according to his deepest conviction live like animals. Second, from 10 or 12 to about 15, when reason starts to develop, and finally from the age of 15 onwards, when the child develops into an adult.

http://en.wikipedia.org/wiki/Jean-Jacques_Rousseau
http://ja.wikipedia.org/wiki/%E3%82%B8%E3%83%A3%E3%83%B3%EF%BC%9D%E3%82%B8%E3%83%A3%E3%83%83%E3%82%AF%E3%83%BB%E3%83%AB%E3%82%BD%E3%83%BC
ルソーは、人間は二度生まれる。一度目は生存するために、二度目は、生きるために、と述べました。
http://plaza.rakuten.co.jp/masaueitimoto/10002