He was a fool, said Willow calmly to Klein. There are many who refuse their responsibilities. Fooling themselves they search for a 'higher ideal'. He was a fool.
What are responsibilities? said Klein laconically. He knows. Responsibility, my dear, is another word for self-interest. For survival.
She looked at Klein uncomprehendingly.

Chapter 4 (p. 206) - The Sundered Worlds (1965)