German translation by Mythologie der feen und elfen (1828) quickly appeared. Jacob Grimm is said to have praised the work. It was popular among Victorian folklore researchers and literary figures in its day; an expanded edition appeared in 1850, and a newly prefaced one in 1860. It has subsequently been reissued intermittently up to modern times, vindicating Keightley's own "high hopes of immortality for his work" in his preface, despite an early biographer calling this "pretentious". Keightley is regarded as an early practitioner in England of the Brothers Grimm's approach to the study of myth and folklore, exploring the parallels between the myth of a nation to the religions and mythology of other regions. Thus Keightley began by attempting to trace fairy myth to Gothic and Teutonic roots, as the Grimms had done for elves. Keightley, like the Grimms, eventually reached the conclusion that it was implausible to trace a myth to an ultimate single source, and that parallel myths can be explained by the "Enlightenment idea that human nature [that] is uniform," and similar experiences and responses are shared across mankind. Conflict over credit Keightley had contributed to T. Crofton Croker's Fairy Legend (1825–1828), and Keightley being stimulated to write his own book was perhaps the most important consequence of Croker's publication. But it was an uneasy situation, as Keightley was clearly peeved at Croker for not properly acknowledging Keightley's aid, even though in the preface to the 1850 edition, Keightley explains the circumstances more cordially, addresses Croker as "one of my earliest literary friends in London". A selection in Fairy Mythology was an Irish mermaid story entitled "The Soul Cages," which turned out to be a hoax of sorts. The male merrow story was first printed in Croker's anthology, but Keightley came out with a later edition of the Fairy Mythology he added a footnote to this tale, proclaiming he "must here make an honest confession," and informed the reader that except for the kernel of the story adapted from the German story of "The Peasant and the Waterman", this Irish tale was entirely his invention. Publication history The Fairy Mythology underwent several printings (1833, 1850, 1878, etc.) in the 19th century.{{Refn|group="lower-alpha"|It was issued in 1833 with a more long-winded title: The Fairy Mythology: Illustrative of the Romance and Superstition of various Countries.}} The 1878 edition was reprinted a century later retitled as The World Guide to Gnomes,