Just watched a video by some German neurologist, or brain researcher as they call him, and he said "learning needs to be meaningful, needs to go under the skin and the only emotional state where this happens is that of rapture, or enthusiasm. And children, quite naturally, have this state about 20 to 50 times a day and then a watering can pours some fertilizer into their brain and real learning, experience and retention takes place, this is natural learning. Teaching by reward and punishment makes children become addicted to reward or punishment and does not allow for this deeper kind of learning out of their own efforts."