Hardening is a good way to put it. It is the ego that hardens, and I suppose when depends on how much fire the clay is exposed to at what age. Sometimes the child does not have the luxury of playing with different shapes and designs before having to put it in the kiln and get it ready for use. If the world threatens then I must know who I am if I am going to device my strategy to deal with it. Sad I suppose, but all life experience is valuable, and some things need to be lived to be truly understood. At least there is always the option, no matter how hardened the heart has become in life, to be born again.