Consider the act of reading a novel. Doesn’t matter what the novel is, it could be Moby-Dick or Twilight, a thin mystery or a thick multi-generational epic. The content is not what’s important. Focus on the actual physical act of reading a novel. Regardless of the density of words or ideas, the idea here is this act of picking out a comfortable spot which one plans to occupy for a certain extended period of time as they sink into the world opened before them within the pages of the book is act of faith. Or, perhaps more accurate, a gamble of one’s free time. Or, put still another way—and one that was a common point of view toward the act of reading a novel for many people until the 20th century, equivalent to eating a bowl of pudding. That is pretty much the interpretation of time spent reading a novel which Henry James expends so much time, energy and words fighting against in "The Art of Fiction" as well as many of his other works of critical non-fiction.
The novel throughout the first half of its existence—which includes the entirety of the 19th century when it underwent the evolution something that barely resembles what we consider a novel today toward almost entirely the thing we consider today—lived with a bad reputation. In comparison to poetry, stage drama, and opera, the storytelling mode of the novel was consistently facing a losing battle for recognition and respect. To frame things without a surprising accurate modern allegorical perspective: the novel was the punk rock of its time. Or, to get back to Henry James again, a novel was viewed as eating pudding while great epic verse or the writing of a five-act tragedy was full course meal.
The saddest part of the history of the novel is that even a great many of those actually made a living writing novels felt the same way. Even some of the practitioner of the very act of writing novels looked snobbishly toward their final product as unworthy of even mediocre poetry or writing farce to perform on stage. This, for the most part, does not include those famous names who helped to revolutionize the form: the Brontes, Austen, Dickens, Melville, etc. In fact, most of those successful writers who viewed their creative act as equivalent to making pudding instead of cooking a full feast have been forgotten to history, left in the dusty archives of the writers which James consistently argues should not be considered the progenitors of a worthy form of telling stories.
It is against those writers who essentially just rewrote the same story over and over and the tellers of embarrassing sentimental romances and the adventure novels without characterization which James rails against. Expressly in "The Art of Fiction", but very often in more oblique ways in other critical essays, that the real power of the novel, especially in its future conceptualizations, would be found in those written by authors who used that very power of the time it takes to read to transform its full realization as an art that “lives upon discussion, upon experiment, upon curiosity, upon variety of attempt, upon the exchange of views and the comparison of standpoints.” The aspect of the novel which had long been its bone of contention among those who viewed it with disdain could instead, according to James, becomes precisely the aspect which it elevated to it prominence and respect.
James uses his critical analysis to reveal how the novel is an interactive creative form that poetry or drama or anything else yet invented could never be. It is the very act of indulgence, of putting off other things, of spending considerable time with fictional creations sprouting from the mind of another that provides the ability for a novel to become an experience that is much more than replication of life. Unlike a play, a fiction is not merely recreated for view. The reader of the novel must provide the visual imagery keyed to the descriptive clues provided by the writer. And unlike epic verse, the novel allows for digression from the main plat and exploration of the lives of secondary characters to create a more expansive world for the reader to explore.
The ultimate argument that James makes is that it is this expansive quality of the novel and its ability to take the reader out of the real world that is the essential equality that separates the novel from all over literary forms. And since nothing else can do what it does, that possibility alone should be more than enough to elevate what had looked down upon an unworthy art form to a status of equality. He then goes on to assert another fundamental property of the novel which permeates his critical writings: that the act of being freed from conventions and rules and generic regulations and codified expectations of what a novel should to allow it to organically evolve into what it could be will ultimately elevate the novel above existing literary forms. It is an expectation which has since been proven remarkably accurate.