Because your question searches for deep meaning, I shall explain in simple words. ---- Dante Alighieri
There were several aspects to what made Diablo Canyon the key to everything that had come before, It was both a place and a goal. It also was part of what this earth and its nature is all about. Of course, also for me, with some changes to the novellas, it became the novel.
For the novel, mysticism was important, but so, was the physical reality of the earth on which we live. Is it really, what we think? We know that it's made up of many chemical aspects (names most of us have never heard). Our flesh, all that is below, and around us is made up of atoms/nucleus and whatever, is beyond that. What holds it together and gives it form is energy. This is the reality of life even though we operate on a physical level as though that what we see and feel, is all there is.
What makes Diablo Canyon important, beyond what I ever intended is the question of the importance of physical ley lines. Do such energy lines exist? And if they do, how might that impact human life? In the book, the climax uses not only energy, what we see, but the spiritual stories that grew from the beginning of humans collecting them from religion and mythology. Are those stories fiction or might they reflect a reality that a more 'sophisticated population' rejects?
In the ending of Diablo Canyon, is presented a question. How do humans, even those with spiritual powers ,fight evil, that which would destroy or dominate them-- or can they?
The story, of course, depicts all of this, but there is something else. In some ways, the cover is about marketing, but it also can be the heart of the book, inspiration for reader and writer.
For Diablo Canyon, I came to see it needed more than images that would show the romantic couple, but go beyond for how they would fight wrong? Could a cover, one with three couples do that? Or might one couple depict the book's theme?
As usual, when putting together a cover, I looked at a lot of images. Most, I had purchased years earlier with no precise idea of how I could use them. Then, I came across two that worked for what I believed the book needed.
The hero, of the book, was a 'druid', running a detective agency to solve problems that went beyond the physical. The image had to look like someone who could take charge. The one I found had an expression that looked as though he could deal with whatever was needed. I liked how his hands were tucked into his belt, but fist like. That expression in his eyes said he was looking for how he would use his power. He was in no hurry to rush into action, but would be ready at the instant he knew the time was right.
The heroine, his love interest, had been in the second book. Except there, she was an angel and spirit guide. To deal with what was happening in Diablo Canyon, the powers above, requested she become a human to bring strength to the needed warriors, along with her own, to fight for right. Some humans today think the spirit world has all the powers-- what if they were given the power to use and expected then, to do it. This one-time angel didn't feel she had those abilities, but turned out, she had a lot more going for her than she knew. It's all about ... energy.
For readers and writers, covers can impact the stories for which they are supposed to represent. I think this one did that for me. The rings in my dream are on it because they represent a love that hovers over a canyon that could lead to destruction or happily ever afters. And the hero and heroine on the cover, depict two ways of dealing with a huge problem. There is the suppressed power as the man waits for that moment where it will be unleashed. Then, the drawing up of spiritual energy by what might seem delicate hands.
Having three novellas, then a novel with the spice the others didn't have, bothered me, in how I promote them. Four books? Three? One? If someone doesn't read the whole blurb and buys the novellas and then the novel, they might feel they were cheated. The novellas do have one extra feature-- Dante's quotes fit each chapter. What a philosopher/poet he was.
Images purchased from Romance Novel Covers, and Stencil.