Negative space

It’s not so much what you say but what you don’t say, not what you write but what you don’t write, not what you paint but what you don’t paint. The impression that any word makes on the reader depends on the words around it. The impression that one splash of color makes on the viewer depends on the colors around it.
The most obvious negative space is silence in song, monochrome in painting, blank space on a page of writing. But negative space is really just one end of the scale. We might say positive space is on the other end. Between them, there are pixels of subject that each participate to varying degrees in subjectness.
Now, is there really such a thing as purely negative space? How can we make such an assumption, on behalf of either the creator or the consumer? How can we decide for them what parts they will consider subject and what parts they will consider background?
Like a little girl who holds her father’s hand while waiting in line for the train. Everyone else is leaning side to side, jumping up and down—trying to get a glimpse of the train, the door, how full it’s getting. The girl is crouched down playing with an ant. Who could have seen the ant in a painting titled “In Line For The Train?”
Some writers talk about “filler.” In the middle of a novel, there may be pages that are not the writer’s best work, but they get the book to a total page count and they progress the story along. Filler is still positive space. It’s words—the main medium for the art form of writing. But might we say that filler is closer to negative space than, say, the climax?
As a writer, what am I letting the reader assume? How much relatively negative space am I giving them to fill with their own imaginations? The reader is not completely loosed. Even blank white pages will confine their thoughts and feelings to a certain section of mental-emotional possibilities. How meticulously can I reduce the number of possibilities?
If I have written a poem to twenty lines and there are three possibilities for the conclusion at which the reader will arrive, should I write a twenty-first line to reduce the possibilities to just one? How does it change the experience of the reader to make the leap on their own? To solve it like a puzzle. I would say there is some joy and sense of achievement to be derived from this independence.
Works of art that utilize negative space may be more enjoyable in a world filled to the brim with positive space. We see these trends in “minimal” art—one-line drawings, flash fiction, etc. In a boring world full of background, detail is desirable. In a busy world of information overload, detail is overwhelming.