This book is about Nikola Tesla
Consider:- Nikola Tesla and Mark Twain were good friends
- The premise of the story is a man who gets sent back in time with massive knowledge of future technology, and attempts to create as much of it as possible, but most people don't see any use in it aside from diversions and minor things. Many years later the general public begins to 'discover' these technologies, with little-no record of their past existence.
- They were opposed by someone with little skill who mostly knew how to display.
- Tesla is a devout Catholic.
Hank Morgan had schizophrenia.
If we go by the assumption that his journey to the past was All Just a Dream, we still have to explain why Clarence, who shouldn't even exist has written down the last pages of the manuscript. I'm no expert at mental disorders, but it could be that Morgan suffered from both hallucinations, making him believe that he was in the Middle Ages, and multiple personality disorder, making him believe that he was both himself, the king, Merlin, Clarence and maybe even some other characters.