Gaiman goes on to talk about why it is the best book in the world. He said,
It was funny in strange ways. It was filled with words. And while all books are filled with words, this one was different: it was filled with magical, wonderful, tasty words. It slipped into poetry and out again in a way that made you want to read it aloud...I did, in fact read it aloud, not to children, though I can't wait until my grandson is old enough for me to read it to him, but I read it aloud for myself and my pets sitting on the couch nearby. I wanted to experience the whole book, not just the one that lived in my head as I read silently. So my pets got to hear the whole thing out loud.
Now about the plot. Well, there is a prince, Zorn, who disguises himself as a penniless minstrel, and a princess, Saralinda, who is bewitched and can only say, "I wish him well." There is a Golux, who is born of an ineffectual witch and a drunken wizard. There is also an evil Duke, a Hush and a Whisper, and a Hagga, who cries gems. There is also a terrifying Todal. The mere mention of his name makes a guard's hair turn white instantly.
Prince Zorn decides he will rescue Saralinda from the evil Duke but is captured instead. With the help of the Golux, who doesn't have a very good memory, Zorn is given a task to find 1000 gems and to start all 13 clocks, which are stuck on 10 minutes to 5. This task must be completed in 99 hours or he will be chopped up and fed to the geese.
You can tell from the summary that much silliness ensues. And words are magical elements of the story. I found myself laughing at the ways Thurber put words together to make fun of the characters and of the readers. Gaiman described it this way, "Thurber wrapped his story tightly in words, while at the same time juggling fabulous words that glitter and gleam, tossing them out like a happy madman, all the time explaining and revealing and baffling with words." And, as often happens when masters put pen to paper, these words often have double meanings. Words might mean one thing to children and quite another to adults, which gives the book a timeless and often humorous quality.
Oddly, Thurber, who is known for his own illustrations, did not illustrate this book. Apparently by the time he wrote The 13 Clocks in 1950 he was legally blind so he sought help from other illustrators. In my mind the illustrations are just as goofy as the book, so they match. The book, which had been out-of-print for many years, was reissued in 2008 and is well worth the hunt it may take to find a copy.