Mr. Socks Fox is one clever vulpine. Like many Seuss characters, he's energetic, playful, and can do some crazy acrobatics when the moment arises. He's also very good at word games—perhaps too good.
Before we talk about Fox and his blue socks, we'd like to discuss a little history regarding foxes in culture. It may only appear to be a simple book about tongue twisters, but Dr. Seuss is dipping his pen into some pretty deep mythological ink here.
The fox has had a long and venerable place in many mythologies across the world. It appears in legends and folktales everywhere from Japan to America, Greek to Peru. Despite the considerable distance between these cultures, the fox plays a similar role in each: the cunning trickster. It's even been suggested that our word shenanigan came from the Irish sionnach, meaning "fox" (source).
Generally, these legends and folktales revolve around a fox spirit tricking a human or animal into getting something it wants—think the Iroquois's "The Hungry Fox and the Boastful Suitor". Usually, the fox's tactics and trickery are entirely about subverting language and fooling the unwary mind.
And this image of the fox continues to play even in modern cultures. Machiavelli famously said that his ideal king should imitate the fox and the lion—the lion for its strength and bravery, the fox for its cunning and intelligence. Disney modeled their version of Robin Hood after a fox since the character uses tricks rather than brute force to "borrow" money from the rich. Naruto of the Naruto manga series is possessed by a fox spirit and has a childish, trickster personality. And the list goes on.
Mr. Socks Fox plays off all this mythology in his character. He's tricky, yes, but he's not trying to get something from Knox. He just enjoys using tricky language to show off and one-up Knox at every turn, referring to his word play as "tricks" to be performed (7.3).
He's also a pretty boastful guy, but again, in a tricky way. He doesn't outright sing, "I'm the best a-round! Nobody's ever going to take me doooooooown!". But he does promise to show Knox an "easy thing to say" right before reciting a tongue twister more difficult than the last one (15.3-4). Yeah, he's that kind of guy.
But unlike the mythological fox—who tends to get away with stuff pretty easily—Fox does get his comeuppance. At the book's end, Fox lays down a long-winded, awesome, and tad showboaty word game about tweetle beetles. It pushes Knox a little too far, and he retaliates with a super-mega-ultra-fantastic tongue twister of his own. He also shoves a dazed Fox in socks into the bottle with the tweetle beetles (caging the beast, as it were).
Like a foxy folktale, Fox's fate hints of a moral to the story—showing off isn't the best of ideas. But as with most Seuss books, it's a slight and subtle moral. No Aesop endings here.
The book ends before we find out what happens to Fox. Did he learn his lesson and repent from his trickster ways? Maybe. But we secretly hope not.