Like water from a natural spring vs. Opening a hole in the hard rock and locating a new water vein

"Writers who are blessed with inborn talent can freely write novels no matter what they do - or don't do. Like water from a natural spring, the sentences just well up, and with little or no effort these writers can complete a work. Occasionally you'll find someone like that, but, unfortunately, that category wouldn't include me. I haven't spotted any springs nearby. I have to pound the rock with a chisel and dig out a deep hole before I can locate the source of creativity. To write a novel I have to drive myself hard physically and use a lot of time and effort. Every time I begin a new novel, I have to dredge out another new, deep hole. But as I've sustained this kind of life over many years, I've become quite efficient, both technically and physically, at opening a hole in the hard rock and locating a new water vein. So as soon as I notice one water source drying up, I can move on right away to another. If people who rely on a natural spring of talent suddenly find they've exhausted their only source, they're in trouble." (#23 p.43)