For Melville, the whale presents a special problem for the author: it's a real animal; yet almost none of his readers have actually seen one or even an accurate picture of one. The author cannot count on a few telling details to conjure up an image in the reader's mind. The problem is also an opportunity (as are all problems, if you read management-training books, which I have; which is to say I read one a long time ago)--the whale's body is where fiction meets science, god meets flesh. The whale pushes earthly powers of representation to its limits.
At these limits, Melville (or Ishmael? Who can tell?) seems to throw up his hands once again:
For all these reasons, then, any way you may look at it, you must needs conclude that the great Leviathan is that one creature in the world which must remain unpainted to the last. True, one portrait may hit the mark much nearer than another, but none can hit it with any very considerable degree of exactness. So there is no earthly way of finding out precisely what the whale really looks like. And the only mode in which you can derive even a tolerable idea of his living contour, is by going a whaling yourself; but by so doing, you run no small risk of being eternally stove and sunk by him. Wherefore, it seems to me you had best not be too fastidious in your curiosity touching this Leviathan.
Melville was an imaginative guy, but he did not foresee Jacques Cousteau. Today, I'd expect few among us to say that we have no "tolerable idea" of what a whale looks like. Even though all I've ever seen with my own eyes amounts to this--
--I have no trouble picturing "whale" in my mind's eye. In today's imagination, thanks to film and TV and super-duper underwater photography, the whale has been normalized. It has also, fortunately, been (mostly) saved from extinction.
Because of these technologies, we have now become "fastidious in our curiosity" about pretty much everything in fiction. We demand to know exactly what every object, person, animal, and setting in a story looks like. Authors must create credible imagery, because today's readers are much more familiar with the flora and fauna and activities of the world, even in those parts that are very distant from us. And if we're not familiar, we can pretty easily look these things up. This pressure sometimes leads to episodes such as the one in Ian McEwan's Saturday, when we get umpteen pages of full-on brain surgery that feel, to me, more like "proof of research" than a contribution to the story.
"Show don't tell" means visual showing above all. Precise visual detail is required in fiction (as I read in some how-to-write-a-novel book, whose name or author I cannot remember now) because of film and TV have become our dominant modes of storytelling. Readers' imaginations have been so shaped by moving images that fiction that deviates from this structure now seems "wrong." I also remember Zadie Smith remarking in an interview that she had discovered, to her chagrin, that her novels contained "commercial breaks." It's the same for a lot of us who grew up watching television; I have no doubt that my sense of narrative rhythm, and my desire to put *** between paragraphs at certain points, is driven by a subconscious voice intoning, "and now a word from our sponsor."
But what would it be like, as authors, to reject--just as an exercise--this tyranny of the visual? I'm not saying don't do your research (although I am saying: don't go whaling). Is it even possible to disentangle ourselves from the movie / television / YouTube complex and structure stories on some other principle? What is different about books that were written before these things colonized our collective gray matter? Are we even capable of understanding, let alone writing stories without that filter?
I'm not at all sure, which is a little scary. But I am going to be more conscious of where film or TV or the Internet is shaping the way my stories unfold--or my expectations for others' stories. I'm a little too used to thinking I should see a story, when maybe I could experience it in some other way.