'That's a great relief to me,' McKie said. And he wondered: What did he really mean by that? This thought elicited another, and McKie said: 'Whenever I run into this problem of communication between species I'm reminded of an old culture/teaching story.'

'Oh?' Bolin registered polite curiosity.

'Two practitioners of the art of mental healing, so the story goes, passed each other every morning on their way to their respective offices. They knew each other, but weren't on intimate terms. One morning as they approached each other, one of them turned to the other and said, 'Good morning.' The one greeted failed to respond, but continued toward his office. Presently, though he stopped, turned and stared at the retreating back of the man who'd spoken, musing to himself: 'Now, what did he really mean by that?'''

Bolin began to chuckle, then laugh. His laughter grew louder and louder until he was holding his sides.

It wasn't that funny, McKie thought.

--Frank Herbert, "The Tactful Saboteur"