“The most important thing in communication is to hear what isn't being said.”
Variant: The most important thing in communication is to hear what is not being said.
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Peter F. Drucker 180
American business consultant 1909–2005Related quotes

“The most important thing to the Christian community is not the environment but evangelism.”
"The Fish Gate" sermon (September 2, 2007)

A Mathematician Grappling With His Century (2001). Quoted in slide no.22 https://edpolicy.stanford.edu/sites/default/files/events/materials/elgw-boaler-ppt.pdf
Context: I was always deeply uncertain about my own intellectual capacity; I thought I was unintelligent. And it is true that I was, and still am, rather slow. I need time to seize things because I always need to understand them fully. Even when I was the first to answer the teacher's questions, I knew it was because they happened to be questions to which I already knew the answer. But if a new question arose, usually students who weren't as good as I was answered before me. Towards the end of the eleventh grade, I secretly thought of myself as stupid. I worried about this for a long time. Not only did I believe I was stupid, but I couldn't understand the contradiction between this stupidity and my good grades. I never talked about this to anyone, but I always felt convinced that my imposture would someday be revealed: the whole world and myself would finally see that what looked like intelligence was really just an illusion. If this ever happened, apparently no one noticed it, and I’m still just as slow. (...)At the end of the eleventh grade, I took the measure of the situation, and came to the conclusion that rapidity doesn't have a precise relation to intelligence. What is important is to deeply understand things and their relations to each other. This is where intelligence lies. The fact of being quick or slow isn't really relevant. Naturally, it's helpful to be quick, like it is to have a good memory. But it's neither necessary nor sufficient for intellectual success.

“The thing that's important for me is to remember what's the most important thing.”

The Illustrated London News (25 April 1931)

Bill Moyers interview (2002)
Context: I used to say that arts were talked about in the arts and leisure page. Now, why would it be arts and leisure? Why do we think that arts are leisure? Why isn't it arts and science or arts and the most important thing in your life? I think that art has become a big scarlet letter in our culture.
It's a big "A." And it says, you are an elitist, you're effete, or whatever those things... do you know what I mean? It means you don't connect. And I don't believe that. I think we've patronized our audiences long enough.
You can do things that would bring people to another place and still get someone on a very daily mundane moving level but you don't have to separate art from the masses.