Imagine a thread, woven over another over another. One, perhaps, is a navy blue, the other a metallic color, gold or silver. In between, sparser, you might have a red or violet. Notice the alternation of colors isn't done strictly for aesthetic reasons. If you didn't weave the threads together, the tapestry would fall apart. Nevertheless, it's the alternation of colors that gives the fabric a richer tapestry than the sum of the parts of the colors.
I'm still reading Kay Kenyon's Bright of the Sky. What's thrilling about this book is that she knows how to put a story together, and even if you know what she's doing, you still shake your head when you see the final result.
In a section I was just reading, the protagonist, Titus Quinn, is traveling on a magical boat on the Lethe-like River Nigh to the Ascendency, the big magical city in the realm of the Entire, a parallel universe next to ours. The trip itself is what playwrights call Opening and Closing of Doors, meaning a person has to get from one place to another for the plot to advance in that other place. This is where inexperienced writers get hung up. They either do a long, slow, dull description of the transition, in which nothing advancing the plot happens, or they just say "and then he was there," without the reader actually feeling the transition. The second option is better than the first by far, and is sometimes necessary, but the writer and reader both feel hollow when it happens, like the Wizard's magic strings were momentarily revealed from behind the curtain.
So what to do? What Kenyon gives us is a mystical dream-like sequence in which Quinn encounters the seer-like Navitar who guides the boat. The Navitar says a lot of things about pulling threads, makes vague hints about the continued existence of Quinn's wife, whom he thinks is dead, and suggests that the "threads" of the universe converge through him. I don't know exactly what it means yet, but I know Kenyon is setting up something that will become important later in the book, or possibly the next.
And then, boom – there's the Ascendency. And I know I was there, because something happened on the way. But the thing that happened was the advancement of an entirely different plot thread, a gold strand weaving over the blue I'd been following before. And as soon as it happened, I realized what she had done, but was delighted nevertheless. It was like a magician who waves his hand around as a distraction while the other hand slips your card to the top of the deck. But better, because the distractor hand was simultaneously setting up an entirely different trick to surprise me down the road.
The storyteller-as-weaver trope, I admit, is a terrible cliche. But people don't talk much about why. Vaguely we all know as we write we should always be "advancing the plot," whatever that means. But the plot isn't a big chunk of granite you heave forward across the floor. With longer fiction especially, the plot is a twisting multithreaded tangle of threads that need to reinforce each other and have to all tie up neatly at the end.