Many nursery rhymes have been argued to have hidden meanings and origins. (1765?–1842), for example, wrote four volumes arguing that English nursery rhymes were actually written in 'Low Saxon', a hypothetical early form of Dutch. He then 'translated' them back into English, revealing in particular a strong tendency to . Many of the ideas about the links between rhymes and historical persons, or events, can be traced back to Katherine Elwes's book (1930), in which she linked famous nursery-rhyme characters with real people, on little or no evidence. She assumed that children's songs were a peculiar form of coded historical narrative, propaganda or covert protest, and rarely considered that they could have been written simply for entertainment.
There have been several attempts, across the world, to revise nursery rhymes (along with fairy tales and popular songs). Even in the late 18th century we can sometimes see how rhymes like "" were cleaned up for a young audience. In the late 19th century the major concern seems to have been violence and crime, which led leading children's publishers in the United States like Jacob Abbot and Samuel Goodrich to 'improve' Mother Goose rhymes.
Early folk song collectors also often collected (what are now known as) nursery rhymes, including in Scotland and in Germany and in (1806–1808). The first, and possibly the most important academic collection to focus in this area was 's, (1842) and in 1849, in which he divided rhymes into antiquities (historical), fireside stories, game-rhymes, alphabet-rhymes, riddles, nature-rhymes, places and families, proverbs, superstitions, customs, and nursery songs (lullabies). By the time of 's (1895), folklore was an academic study, full of comments and foot-notes. A professional anthropologist, (1844–1912) produced in 1897. The early years of the 20th century are notable for the illustrations to children's books including Caldecott's (1909) and 's (1913). The definitive study of English rhymes remains the work of .
In the early and mid-20th centuries this was a form of , concerned with some of the more violent elements of nursery rhymes and led to the formation of organisations like the British 'Society for Nursery Rhyme Reform'. such as strongly criticized this revisionism, on the grounds that it weakened their usefulness to both children and adults as ways of symbolically resolving issues and it has been argued that revised versions may not perform the functions of for children, or allow them to imaginatively deal with violence and danger.