And here you thought the only people celebrating a birthday today were Spike Lee and Henrik Ibsen. It's also the fortieth anniversary of Eric Carle's classic children's book The Very Hungry Caterpillar, a vibrant, tactile, and poignant tale of a voracious young caterpillar's journey to butterflyhood. Since the book was first published in 1969, it has sold more than 12 million copies in 45 languages. Carle, who turns 80 this year, is still going strong (check out his blog), and Philomel has just published a new hardcover pop-up version of The Very Hungry Caterpillar ("a stunning, tour-de-force pop-up," says Amazon.com).

The famed caterpillar actually began his life as an ordinary worm. After some fortuitous experimentation with a hole puncher, Carle got to thinking about a bookworm and created A Week with Willi Worm, which ended with the title character growing into a morbildy obese worm. "I showed it to my editor, Ann Beneduce, and she didn't like the worm so much," explains Carle in a video on his website. "She said, 'How about a caterpillar?' And I said, 'Butterfly!'" And the rest is history.

What accounts for the enduring appeal of the red-faced caterpillar made from Carle's distinctive collages of hand-painted tissue paper? "Aside from the story, aside from the graphics, the touchable holes, and the learning that's camoflaged in there, I think it's a book of hope: you can grow up, fly into the world with your talents," he says. "I'm gratified that it has had such an impact." For further proof of the book's impact, pay a visit to the Eric Carle Museum of Picture Book Art in Amherst, Massachusetts or check out the Google homepage, which today welcomes spring with a Carle-designed Google Doodle.