'The Very Hungry Caterpillar' Turns 50: 'It's [a] Message of Hope,' Says Author Eric Carle

If you ask author Eric Carle, he can’t quite tell you why The Very Hungry Caterpillar is still so popular today.

“I believe most children can identify with the helpless, small, insignificant caterpillar, and they rejoice with it when it turns into a beautiful butterfly,” he muses to PEOPLE. “It is an affirmation to all children. It says: I too can grow up. I too can unfold my wings and fly into the world. I think it’s this message of hope.”

That hope has turned into success some can only dream of: The Very Hungry Caterpillar turns 50 this year, and since its release has been translated into 62 languages, selling more than 50 million copies worldwide.

“It is very moving to me that my books have been enjoyed by generations of readers,” 89-year-old Carle says. “The storyline is surprisingly universal.”

Sharing that he often receives letters from special education teachers about how students respond to his books — “perhaps because of the bright colors and bold shapes in my illustrations,” he guesses — there is one fan letter that’s stood out to him in the 50 years since his most famous tome hit stores.

“A child in Texas wrote, ‘Dear Eric, I would like to visit you but I am not allowed to cross the street.’ ”

To celebrate the big milestone, The Very Hungry Caterpillar events are happening around the country in the weeks ahead (check out the list here), and Penguin released a golden edition of the book, which includes a note from none other than Dolly Parton.

“She’s an amazing literacy philanthropist,” Carle explains. “She started Imagination Library to bring picture books to children who need them … I’m honored that The Very Hungry Caterpillar has been chosen to be in her collection.”

He isn’t working on another children’s book right now — “I have ideas in my idea box,” he shares — but he thinks of his favorite books, which also include Friends and Do You Want to Be My Friend?, often. And when asked if he’d change a thing about The Very Hungry Caterpillar, he has a solid, simple answer: “No.”