It’s Markus Zusak’s “weird optimism” that kept him pushing through to the culmination of his latest work.

The 44-year-old Australian author came to the Iowa City Public Library Monday night for a stop on his tour promoting his latest novel, Bridge of Clay. His novel comes 13 years after the release of The Book Thief, and the process, according to Zusak, was full of ups and downs.

“I don’t want to make it sound like it was torture,” he said, “But there’s some pretty bleak times where you have to say people that you work with and you know and love and they love you — there were times where I had to say, we might just have to face the fact that I can’t write this book, or I can’t write any more books, or I’m washed up, you know, which is a very dramatic thing to say, but that’s kind of how it felt after 10 years.”

Zusak said perhaps his biggest mistake in writing it was losing sight of the fact that the book only had to be perfect at the end.

“I think I wanted everything to be perfect straightaway,” he said. “And so, I toiled meticulously for quite a few years, so much so I kept returning to the beginning of the book all the time. I was just going over and over and over the same thing and always finding something wrong with it, you know, which is what you’re always going to do.”

Zusak initially got the idea for Bridge of Clay in his 20s, writing it out to no “real satisfaction”. He said he believed it to be his best idea and also the idea he was most afraid of.

“It was about a boy wanting to make something great, you know, and so it’s hard not to get trapped into that when you’re writing. You want the writing to be great, as well,” he said.

After a long break and remembering his love of writing, he said, the book came together in four or five months. Despite the long process, Zusak said that he doesn’t regret the time he spent creating it.

“A book is as long as its ideas, really, and it take as long to write as those ideas will take,” he said. “And sometimes, you think of your best things at the 12-year mark. It was just meant to be that way.”

Zusak said he only writes books he’s not sure he can actually write, and he wants to create stories that mean everything to him.

“It’s when you get to that point where you get a bit emotional when you’re reading it, and I think that’s when you understand what it means,” he said. “To me, this book means everything to me, the same way The Book Thief did. After The Book Thief, I thought I don’t ever want to write a book that just means something to me ever again. I only want to write books that mean everything to me.”

The Book Thief,  Zusak’s best-known novel, received immense recognition, winning a Printz award and becoming adapted for the silver screen. Bridge of Clay, he said, has a very different feel to it.

“The Book Thief is always saying ‘Come on, come a little further.’ There’s a whimsical nature to that book, which is actually at odds with its setting,” he said. “Whereas Bridge of Clay is a lot more, ‘Now I’m not going to try to charm you. I’m not going to try to, you know, drag you along all the time.’ That’s why some people have had, I think, bad reactions to it, because they’ve read The Book Thief, and they want to be given a little bit of sugar all the time.”