While I'm sure this varies from person to person, I've developed my own categorisation of that one thing held so dear to writers.
Inspiration Level Zero
"Maybe I can... No. Yeah, just no."
The ground-level reference for the four levels of inspiration, Level Zero is the point where the reserves are dry as Ezekiel's bones. I probably have some sort of plan for the chapter, and maybe I even have a few phrases in mind, but absolutely nothing goes from my head to my fingers, and I don't really care. This is my perpetual state for the story Break Out and rough ideas that vaguely caught my interest like A Murder of Crows.
Inspiration Level One
"Okay, I'm not sure what's going on, but once I get a sentence written, I'm sure the juices will start flowing. ...Okay, maybe once I get the next sentence done... Um, what goes in the next sentence, anyway?"
This is the point where I can pull some stringy, flavourless words out of me if I really try, but it's just not worth it. Maybe I don't have a clear enough idea of what's going on in the scene; maybe I've spent all of my verve on another story, or the same story earlier in the day. If this level persists for a few minutes, it's time to put up the Word document for the time being.
Inspiration Level Two
"So, uh, something happens in this chapter eventually. Not sure what. But hey, words are somehow coming out, so let's roll with it."
This is probably where I spend the brunt of my writing time. It's not very Romantic, but sometimes the words flow silently and unobtrusively. I make progress without feeling terribly excited, but this is the second-best level to feel like I've accomplished something. Beautiful gems can indeed rear their sparkly heads in this level, and joy can abound from this fact. Don't equate satisfaction with inspiration, though.
Inspiration Level Three
"Yes, it's finally the scene I've been waiting for! Writewritewritewrite... okay, this isn't quite turning out right... What am I doing wrong? Um, just keep writing for now..."
Level Three is when I'm honestly excited to write. These are the times that scene that I've watched play in my head several times finally comes into play, and I'm ready to churn it out. My confidence level, however, is no higher than in some lower levels, and once things go a bit sour, I'm not feeling so excited anymore, even if my beloved scene is still in-progress. This was my experience with things like the South Vietnam scenes in Break Out.
Inspiration Level Four
"GAHAHAHAHA!"
This is why people like me have to write. These are the times the scene falls into place while I'm trying to get to sleep, and throwing myself into the story makes my insides twist with emotion so much I have to take breaks to ensure I'm not just about to throw up. These are the times I grab the nearest notepad—regardless if it was reserved for, say, sketching chibis of some of the other girls at church camp—and write down the scene with so much speed and fury I can barely read the script. These are the times my heart's racing, no method can get the words out fast enough, and time vanishes as much as everything else. These are the times of lovely and utter madness.
Of course, inspiration is more of a continuous variable, so I can't always rank myself on one of these levels exactly. Sometimes I'll be just a bit more inspired than Level Two; sometimes I'll be just a bit less productive than in Level Three.
Do you experience inspiration in a similar matter? How would you rank your current level?