"[American] optimism is a national strength and is connected with our original project of mastering of nature. But that project itself is not unproblematic and makes sense only when kept within limits. One of these is the sanctity of human nature. It must not be mastered. ... Human nature must not be altered in order to have a problem-free world. Man is not just a problem-solving being, as behaviorists would wish us to believe, but a problem-recognizing and -accepting being."