''Some were clearly adult rhymes that were sung to children because they were the only rhymes an adult knew," Roberts writes in the introduction.
Others were conceived for children as a way to convey history or life lessons, he writes, while still others are just what they appear to be: ''nonsense verse made up of pleasing sounds."
Roberts makes a fun ride out of figuring out which is which. Reading his work is a bit like falling through a looking glass or opening a wardrobe to discover Narnia -- you never knew there was so much behind something so taken for granted.
I don't want to spoil all the surprises. But I myself was a bit shocked to learn that in the original ''Rub-A-Dub-Dub" it was actually ''three maids" in a tub, while the butcher, baker, and candlestick maker were portrayed as patrons of a naughty side show at the local county fair.
Rather than just being inspired nonsense, Roberts reveals, the rhyme actually began as a bit of barbed social commentary about the secret, seamier pursuits of outwardly respectable businessmen.
Many of the rhymes Roberts tackles have similar origins, beginning in tales of sex, death, cruelty, and British history. Yet he also cautions that some literary scholars have gone too far and read too much into some rhymes.
Some scholars, for example, have theorized a sexual context to ''Humpty Dumpty." The egg-shaped Humpty's fall, they say, could symbolize the loss of virginity, its hazards, and its irreversibility -- a sort of subliminal sexual ''Just Say No" message for kids reaching the age of curiosity.
Hold on, says Roberts. ''Humpty Dumpty," he writes, was the name given to a huge cannon that stood on the walls of a church in Colchester during the English Civil War of the 1640s. After Royalists loyal to King Charles I captured the city, they tried to turn the weapon on the Parliamentarians, only to accidentally blow it up and see it scattered in pieces below, where ''all the king's horses" and men couldn't repair it.
Throughout the book, Roberts leaves plenty of room for alternate theories about many rhymes, and occasionally he meanders into rank speculation and his own bits of social commentary. But he's honest about it, and his occasional tangents are all interesting enough to give ''Heavy Words" the feel of one of his Foot and Mouth Walking Tours of London, from which the book originated.
One small caution: American readers will probably find a few of the included rhymes -- ''As I Was Walking O'er Little Moorfields," ''Turn Again Whittington" -- a bit obscure. Thankfully, though, Roberts has included some American favorites in the US edition, including ''Rock-A-Bye Baby," and a surprising revelation about the origins of that most American of all nursery rhymes, ''Yankee Doodle."
