Jean-Martin Charcot's 1883 lectures on aphasia at the Salpêtrière Hospital were seen as the starting point for the development of a psychology in the work of the famous neurologist. In his lectures, Charcot set out a theory of language function at the cerebral level, distinguishing between the different centers involved in speech production and those necessary for reading. His lectures, which also postulated the independence of ideas from words, were to resonate beyond aphasia specialists, and particularly with alienists. To document this dimension of the reception of neurology in the field of psychiatry, this article refers to Jules Séglas's synthesis on Les troubles du langage chez les aliénés, published in 1892, which summarized the knowledge acquired during the nineteenth century about modifications of expression in madness and whose original ideas were to mark the psychiatric semiology of the early-twentieth century. The analysis details how Séglas cited and adapted Charcot's conceptions to explain the production of incomprehensible speech in idiocy and the formation of hallucinations, thus contributing to the spread of the neurologist's model among his fellow alienists.