It's been 20 years since Mem Fox and Judy Horacek's classic Australian children's book, Where is the Green Sheep?, hit shelves.
But time has in no way dimmed its sparkle, with the charming rhymes (by Fox) and illustrations (by Horacek) still loved by countless children and their carers, having sold more than 2.5 million copies across the globe.
So just how did this bestseller come to be?
"Fox was tootling around on the internet trying to avoid work," Horacek tells ABC News Breakfast, two decades on.
"And she discovered, on my website, a very small etching [of the green sheep] … and she fell in love with it."
Fox confirmed the illustrator's turn of events to ABC Arts, but added that she'd also spotted the same etching at an exhibition of Horacek's work, and been bewitched.
The duo had worked together previously on parenting book Reading Magic (2001) and Horacek had told Fox about her interest in writing a picture book.
"[Fox] sent me an email … and she said: 'I'm in love with the green sheep, you must turn it into a book'," says Horacek.
For Fox, Horacek's etching provoked many rich questions, including: "Why is this sheep green? Does this belong in a rainbow family? Does it go on a quest to find other green sheep?"
But instead of Horacek just writing it, she first asked Fox — who already had many hit children's books, including Possum Magic (1983), under her belt — if she'd like to create it together.
The Green Sheep faces the chop
The duo say working together to create a picture book was highly unusual.
"Normally, most writers would just send a text to the publisher and then the publisher would pick an illustrator who they thought suited the project," Horacek explains.
"The initial idea was that it was for slightly older kids and it was about a goat that was bullying the green sheep for being green."
But, Fox says: "It was going nowhere. It was not going to sell. The title of one of my emails to Judy was: 'Green sheep to abattoir?' Because it was so bad."
Shortly after that rather morbid email, Fox was in the shower — where we often do our best problem solving — and was thinking of a Dr. Seuss book, though she can't recall which one now.
"But it had perfect rhymes, it was an engaging, gorgeous read and it inspired the idea for the first verse," she says.
Still dripping wet, Fox ran to her desk and wrote down the verse, before finishing her shower off.
That verse is what appeared in the final version:
"Here is the blue sheep. Here is the red sheep. Here is the bath sheep. Here is the bed sheep. But where is the green sheep?"
Well, we simply must read on and find out.
'The audition process'
Fox and Horacek were now working on a rhyming book for the zero to three age group, but this didn't make things easier.
"I don't like much about writing for that age group because it's so challenging. For example, people are not aware that in the 190 words of Green Sheep, 188 words are one syllable," Fox says.
And within the four-line ABCB rhyming scheme, the sheep in the A and B lines are connected or opposites (eg. bath and bed sheep, moon and star sheep).
"That's why this book took 11 months for two intelligent women to put together," Fox explains.
Horacek says: "This was in the days of faxing, so I would do little thumbnails of pictures that might go in and [Fox] would make suggestions … It was a big audition process for [which sheep] finally got in the book."
Because of the one-syllable limit, many excellent sheep are penned in to one two-page spread towards the end of the book. That's where you'll find the Carmen Miranda sheep, business sheep (look at him with his cell phone and briefcase, off to do capitalism!) and the narcissistic sheep.
Fox's favourite sheep?: "The near sheep — it's so dramatic, it's so literally in your face."
She says there were also a number of "rude" sheep, including "the dead sheep", that didn't make the cut, for obvious reasons.
Horacek admits: "I drew a sheep in a jar, it was squashed up against the glass and they [the publishers] said 'no, no, that's for seven-year-olds. That's not for nought to threes'."
Green Sheep in the wild
Where is the Green Sheep? was an immediate hit when it was published in 2004.
"Because it's perfect … and it still feels like it was written yesterday," says Fox, who was 58 at the time.
"Green Sheep was one in a run of big hits for me, but a super one that just jumped out."
Horacek says the response to the book over the years has been "quite amazing".
"Nearly every kid knows it. It's very rare to meet somebody who has children of that age, or has had children of that age within the past 20 years, who doesn't know the book. It's just an unbelievable phenomenon."
Of the recent controversy surrounding Cumberland Council's since-overturned ban on children's books featuring same-sex couples, Fox says: "These are foolish minds that need to be ignored, I don't even want to comment on it, it's just so ignorant and stupid, it doesn't bear thinking about."
Fox, who says she's dying to be replaced, has a message for any would-be children's book writers out there: "Don't teach anything — kids can see straight through it and they're not keen on being told anything, they're relying on their parents for that.
"We, as adults, are so desperate to give kids messages, but the purpose of children's books is to entertain and soothe — it's comfort."
The 20th anniversary edition of Where is the Green Sheep? by Mem Fox and Judy Horacek is out now through Penguin Random House Australia.