When the person integrates their shadow and gets the aggressive part of themselves integrated into their personality, their faces harden. Once they integrate that more disagreeable part of them, it's very, very necessary. And so you're full of biological potential that won't be realized unless you move yourself arou nd in the world, into different challenging circumstances. That'll turn on different circuits. It's not merely that you're incorporating information from the outside world in the constructivest sense. It's that by exposing yourself to different environments, you put different physiological demands on on yourself,. all the way down to the genetic level.