In another excerpt from Scott Eyman's “John Wayne: The Life and Legend,” here's Ron Howard on the main lesson he learned making “The Shootist,” Wayne's last film, with Wayne:

“The only thing Duke told me about acting was something he said John Ford had taught him—not to take an emotion to its furthest extreme. Always leave the audience a percentage of the emotion to complete for themselves.”

Cf. with Norman Mailer in 1964:

Art obviously depends upon incomplete communication. A work which is altogether explicit is not art, the audience cannot respond with their own creative act of the imagination, that small leap of the faculties which leaves one an increment more exceptional than when one began.

Feel free to add your own quote on the topic below. 

Why the film wasn't called 'The Straight Shootist.'