It's interesting that the human mind may go through stages that optimize it according to developmental needs. Perhaps abstract thinking is more important at 18 months and then again later in life, than it is at 5? I was recently watching Ken Robinson's talk asking Do Schools Kill Creativity? In it, Ken tells a story about a little girl that is in an art class; the teacher approaches her and asks, "what are you painting?" and the little girl responds, "I'm painting God." The teacher responds by saying, "but nobody knows what God looks like!" To which the little girls responds, "well, they will in a minute." I love that. I wonder how much of a kids ability to do abstract reasoning is forced out of them through our antiquated educational process?