VII. The Organization of the Human Being

But the things you can grasp with your hands outside, the brain does not train that. You could, for all I care, stuff tangible substances through the nostrils into the brain – you would ruin the brain, but it would not be educated. So all tangible matter is of no use to you in building up the brain in the first seven years. Only the finest matter that lives in the light comes into consideration, for example. Only ether comes into consideration.