The author of Guess How Much I Love You, Sam McBratney, passed away on Friday at age 77.

McBratney wrote more than 50 books but is best known for the 1994 publication of Guess How Much I Love You, a tender bedtime competition between two nutbrown hares — featuring the now-iconic illustrations of Anita Jeram. 

Guess How Much I Love You has sold more than 50 million copies worldwide and is considered a children’s book classic. It been translated into 57 languages. 

The phrase “I love you to the moon and back” has itself taken on iconic stature but to its author, at its heart the book was always “a lighthearted little story designed to help a big one and a wee one enjoy the pleasure of being together".

''I love you right up to the moon,' he said and closed his eyes. 'Oh that's far,' said Big Nutbrown Hare. 'That is very, very far.''

We are very sad to hear that Sam McBratney, author of Guess How Much I Love You, has died aged 77. pic.twitter.com/AXfmeAByvo

— Waterstones (@Waterstones) September 21, 2020

McBratney was born in Belfast and graduated from Trinity College Dublin. He was a teacher before becoming a full-time author. He loved touring to support his books and travelled throughout Europe, Asia, Australia, and the US. 

He is survived by Maralyn, his wife of 56 years; three children, and six grandchildren.

McBratney’s highly anticipated companion to Guess How Much I Love You, titled Will You Be My Friend?, comes out this month, with a global publishing date of Sept 29. 

When writing about the hares, I aim to describe moments of emotional significance but with loads of humor and the lightest of touches. 

"This story is about one of those moments. Little Nutbrown Hare’s world suddenly glows with the discovery of friendship," McBratney said about the second book.

His publishers have paid tribute to "a profoundly lovely human being".

“You could recognise his voice in a moment — he was an exceptionally talented wordsmith and always knew exactly what children would enjoy hearing the most. Amazingly humble, he also was a hilarious storyteller and convivial companion. We never had better days than when he would come down from Ireland to visit the offices in London," said Karen Lotz, group managing director of the Walker Books Group, which includes Candlewick Press in the United States.

"Our world dims with his passing, but his legacy of kindness and humor will burn bright and carry on across time and distance through his stories, which have touched the hearts of readers around the globe,” added Karen Lotz.

Walker Books' Donna Cassanova said she is "so lucky to have felt the warmth of his smile".

"I feel such great sorrow at the passing of my dear friend Sam, but also an immense sense of pride, and privilege, to have worked for so long with such a master of his craft. Through the years, as Guess How Much I Love You achieved great success and acclaim, Sam never failed to express his profound surprise at the power of the message within his text. The joy he felt at knowing so many people around the globe connected with the gentle celebration of unconditional love was ever palpable. 

It is also the true mark of the man that he never failed to recognise the role that Anita Jeram’s exquisite illustrations play in the success of Guess How Much I Love You. They were a literary pairing of the highest caliber. Sam faced everything in life, and death, with such great, good grace and humor. He always smiled out at the world, and I feel so lucky to have felt the warmth of his smile."