Jeff, who e-mails me occasionally about writing and books, asked me last week which has been the most difficult book to write and said he suspected it was probably the first one, where you put in the hard slog of turning out upwards of a hundred thousand words without any real hope of it ever getting into print.
His question made me look back at the motivation for writing what started off as The Emperor's Elephant and how things have changed since Caligula was published and again since I decided to try to make a living by writing full time. Each book actually creates a different mental and psychological challenge as opposed to the endeavour, time and imagination you put into it.
Firstly, I think Jeff's wrong. The first book is the easiest to write, because when you're writing it you're totally free from expectation: deep down you know the chances of anyone else ever reading it are as likely as winning the lottery. You can dream, but you don't have to prove anything to anyone except yourself. I wrote The Emperor's Elephant because I enjoyed writing, because I liked the subject, because I was pretty certain I could write a book of some kind and because I found that writing it provided me with the kind of escape that reading books has given me over the years.
When a publisher asked me to turn the first part of The Emperor's Elephant into what became Caligula, I had the motivation of proving to myself I wasn't just a writer; if I could pull this off I was actually on the way to being a novelist. Again, when the book was accepted there was the excitement of being part of a team and the pure adrenalin of knowing you were going to have a first book published.
Claudius, the second book was different, because now there was a weight of expectation which hadn't existed before. Claudius didn't just have to be as good as Caligula, it had to be better. I'd clawed my way through the glass ceiling and now I had to prove I was worthy of staying there.
A few months later came the pure exhilaration of a second deal to write three more books, followed immediately by the horrible knowledge that I was already behind schedule on the first one. I wrote the first forty thousand words of Hero of Rome on the train, knowing that I'd never finish it on deadline unless I went full time, and the next seventy thousand at home knowing that it had to be the best yet, because the rest of my life depended on it.
Now I'm sitting here with a new title on my screen - Defender of Rome - and a new set of problems.
Actually, Jeff, the answer to your question is much simpler ...
The most difficult book will always be the next one.