Fiction is unique among the story-telling arts. Fiction offers no visual images. Unlike film, photography, stage, or oral interpretation, fiction provides only the still and silent words. In all these other forms the audience is passive. The story goes on in front of and external to the viewer.
But with fiction, the story is rendered in the private and silent meeting between the maker of the words and the mind of the reader. If the reader dozes off, the story stops. The story is completed by the reader. When there is no reader the story lies dormant and unfulfilled – unrealized in every sense. The reader brings the necessary action and imaginative power to make the story real. All the writer can provide are the needed words in their precise order.

So, the goal is clear. Do not try to ensure the reader’s knowledge by telling and showing them everything that you think they need to know. This is failure. This is forgetting the reader altogether. Know that at the height of your powers you are a creator of wants. Make the reader want. That is all. See to it that not everything is given but that it is deeply and longingly wanted.
It is what is left out, and the desire this omission stirs in your reader that will lend the story its power.

Note: This post is again the result of a conversation with Ben H. Winters, at LePeeps, 10 March 2016.