In those times of profound ignorance into which some desire to plunge modern society once again, in the Middle Ages, which those elected under universal suffrage have chosen as their ideal, it was very easy, taking advantage of people’s credulity, to inspire in them – and sometimes to impose on them- a belief in ‘miracles’, in other words, in events that were claimed to be outside of natural law. Asleep during that time of such sad and sombre memory, the human spirit has awoken little by little and, despite of obstacles and all kinds of persecution, science has begun to assemble, to herself possess organic laws. Less perfect today than they will be in the future, they suffice however to explain all these events reputed to be miraculous. This development of science, which has taken on vast proportions since the very moment when the French Revolution came to change the face of the political world – is doubtless one of the main reasons why, in 1875, miracles have become rare, unless, of course, those where there is honour or profit to be gained from them. Amongst the doctors who have most contributed to the achievement of this progress in the specialist field which will concern us, we should mention MM Calmeil, Charcot and Valentier. After having studied with great care the sick who are brought to them at centres for the treatment of nervous diseases every day, they have compared them to the more or less legendary accounts of the past and they have come to the conclusion that today one would discover, in individual examples, cases entirely analogous to those which in the Middle Ages, at a time of serious epidemic illness, would have contributed to entertaining a belief in miracles. The method employed by MM. Calmeil, Charcot and Valentiner, will serve as our guide in this study. Louise Lateau, who the Belgian thaumaturges chose as their subject in 1868, is considered by her interested admirers as presenting a phenomenon hitherto unknown to medicine and reputed to be of a supernatural origin. This is an error. And to demonstrate this it suffices to summarise the story of this unfortunate young woman according to the numerous documents supplied to us by orthodox authors and to bear in mind the observations made by doctors who have made a scientific study of nervous diseases and the facts that we have ourselves gathered.