It's almost inevitable that once a nursery rhyme attains a certain measure of fame, some exciting but far-fetched origin story will become attached to it, which endeavours to explain the rhyme's origins in some historical figure or event, or in some myth or legend. And 'Jack and Jill' is no different.
The main culprit in the case of 'Jack and Jill' was Sabine Baring-Gould, who, when he wasn't writing the words to the hymn 'Onward Christian Soldiers' or forgetting what his own children looked like, was putting about exotic but unlikely stories concerning the origins of the 'Jack and Jill' nursery rhyme. In his Curious Myths of the Middle Ages (1866), Baring-Gould asserted that the rhyme 'refers to the Eddaic Hjuki and Bil'.
In the Edda or Scandinavian myth that contains Hjuki and Bil, they are two children captured by Mani, the moon, while they were drawing water. The idea is that when we have a full moon, as the Opies summarise the myth, Hjuki and Bil can be seen with the bucket on a pole between them. But the tenuous similarity between the names, and the water-drawing connection, are appealing but not entirely conclusive. Mind you, sillier theories about classic nursery rhymes have been proposed.
In 2004, Chris Roberts, a librarian at the University of East London, suggested that 'Jack and Jill' is a story about two young people who lose their virginity together, with Jill conceiving a child (perhaps) and Jack running away from his new paternal responsibility. In Heavy Words Lightly Thrown: The Reason Behind the Rhyme
, Roberts draws attention to the surprising presence of the word 'nob' in the second stanza of the nursery rhyme, or at least the version cited by the Opies (and the one we've reproduced above).
'Nob' has meant 'head' since the seventeenth century (a 'nob-thatcher' was a wigmaker, although it sounds like some sort of euphemism or slur), but as a slang word it's more often applied to another part of the male anatomy. Why it should need patching by Dame Dob with vinegar and brown paper afterwards isn't clear, and this interpretation is, again, interesting but not necessarily persuasive.
But then what is 'Jack and Jill' about? Sadly, we will probably never know for sure – assuming, that is, that the rhyme ever had an actual 'meaning'. Many nursery rhymes originated as counting or dancing songs to be sung while children played a game together. But the fact that the nursery rhyme has attracted these two very different interpretations says something about our desire to understand and interpret these timeless children's rhymes. But as for an ultimate meaning? That remains as elusive as ever.