A legend is a narrative of human actions that are perceived both by teller and listeners to take place within human history and demonstrating human values, and which possesses certain qualities that give the tale a feel of magic and fantasy. Legend, for its active and passive participants, includes no happenings that are outside the realm of "possibility," but may include miracles. Legends may be transformed over time, in order to keep them fresh and vital, and realistic. Many legends operate within the realm of uncertainty, never being entirely believed by the participants, but also never being resolutely doubted. The Brothers Grimm defined legend as folktale historically grounded. A modern folklorist's professional definition of legend was proposed by Timothy R. Tangherlini in 1990. Legend, typically, is a short (mono-) episodic, traditional, highly ecotypified, historicized narrative performed in a conversational mode, reflecting on a psychological level a symbolic representation of folk belief and collective experiences and serving as a reaffirmation of commonly held values of the group to whose tradition it belongs. By 1613, English-speaking Protestants began to use the word when they wished to imply that an event (especially the story of any saint not acknowledged in John Foxe's Acts and Monuments) was fictitious. Thus, legend gained its modern connotations of "undocumented" and "spurious", which distinguish it from the meaning of chronicle. In 1866, Jacob Grimm described the fairy tale as "poetic, legend historic." Early scholars such as Karl Wehrhan, Friedrich Ranke and Will Erich Peuckert followed Grimm's example in focusing solely on the literary narrative, an approach that was enriched particularly after the 1960's, by addressing questions of performance and the anthropological and psychological insights provided in considering legends' social context. Questions of categorizing legends, in hopes of compiling a content-based series of categories on the line of the Aarne-Thompson folktale index, provoked a search for a broader new synthesis. In an early attempt at defining some basic questions operative in examining folk tales, Friedrich Ranke (de) in 1925 characterized the folk legend as "a popular narrative with an objectively untrue imaginary content" a dismissive position that was subsequently largely abandoned. Compared to the highly structured folktale, legend is comparatively amorphous, Helmut de Boor noted in 1928. The narrative content of legend is in realistic mode, rather than the wry irony of folktale; Wilhelm Heiske remarked on the similarity of motifs in legend and folktale and concluded that, in spite of its realistic mode, legend is not more historical than folktale. In Einleitung in der Geschichtswissenschaft (1928), Ernst Bernheim asserted that a legend is simply a longstanding rumor. Gordon Allport credited the staying-power of some rumors to the persistent cultural state-of-mind that they embody and thus "Urban legends" are a feature of rumor. When William Jansen suggested that legends that disappear quickly were "short-term legends" and the persistent ones be termed "long-term legends", the distinction between legend and rumour was effectively obliterated, Tangherlini concluded.