"The Fremen were supreme in that quality the ancients called "spannungsbogen" — which is the self-imposed delay between desire for a thing and the ac… - Frank Herbert

Jessica stopped beside him: ‘What delicious abandon in the sleep of a child.’
He spoke mechanically: ‘If only adults could relax like that.’
‘Yes.’
‘When do we lose it?’ He murmured…
‘We do indeed lose something,’ she said.

It's easier to be terrified by an enemy you admire.

I know the evil of my ancestors because I am those people. The balance is delicate in the extreme. I know that few of you who read my words have ever thought about your ancestors this way. It has not occurred to you that your ancestors were survivors and that the survival itself sometimes involved savage decisions, a kind of wanton brutality which civilized humankind works very hard to suppress. What price will you pay for that suppression? Will you accept your own extinction?
-The Stolen Journals