"Please, come in." Being a charlatan, or the question of trustworthy knowledge.

With these words from the 1860s, Guido Bennati (1827–1898), an ambulant quack from Pisa, introduced himself at his arrival at the market places in the Italian Piedmont. By calling himself a charlatan, Bennati did not disqualify his art. He called his profession by its real name, and he underscored its value: he was a self-styled practitioner in the lower regions of the medical profession who, in Italy, during the time of the Risorgimento, were still licensed to sell some kinds of external remedies and to perform external operations. They seemed to be making themselves heard everywhere. From England to Italy, from France to Spain and the Americas, markets and newspapers were filled with their advertisements and remedies. “Charlatan,” while a profession, meant something different in other linguistic contexts. Just across the border, in France, the journalist and writer Jean-Baptiste Gouriet (1774-1855) had published a compilation of the most famous charlatans that visited Paris from ancient times to the present day. In so doing, he specified that the term included the jugglers, jokers, jesters, operators, acrobats, crooks, swindlers, soothsayers, card-pullers, fortune-tellers and all the characters who have made themselves famous in the streets and public squares of Paris. Gouriet connected their stories to the history of theatre, entertainment, and illusion, but also to their use of the public space and their itinerant life (Gouriet 1819). Traveling from one marketplace to another, dealing in exotic objects and remedies, organizing shows and exhibitions, performing miraculous healings by appealing to the curative power of words and liniments, charlatans have infested Paris and traversed Europe at least since early modern times. The category included advocates for the elegant dog, the sage donkey, and the talking horses, a conversation that – as Daniel Gethmann shows in his article below – made its way into the scientific debates of the twentieth century. In that sense, tracing the history of charlatans and talking horses can be a means of seeing and understanding the changing frontiers of science. As Nathalie Richard develops in her epilogue, the science of modern charlatans syncretizes elements of a popular culture that far from having “no history” is rather constituted with elements borrowed from the cutting edge of the modernity of its time. As the classic mountebank he was, Bennati arrived in the Italian towns accompanied by a parade of exotically dressed musicians and entertainers (Fucini 1921, translated by and quoted in Gambaccini 2004, 200). Like many other European traveling doctors, Bennati appealed to “drum and trumpet” theater performances, old routines that in the nineteenth century had incorporated the “ethnographic parade,” in the style of Phineas Taylor Barnum’s circus, which originated in the US as traveling medicine shows: the association of a “doctor” with a Native