In 1854 Jean-Pierre Falret published an essay arguing against the concept of monomania, a nosological form which structured most French classifications of insanity until the middle of the nineteenth century. The historical importance of the text is already well known, since it marks the beginning of the decline of the monomanias. But the aim of this Classic Text was twofold: not only to cast doubt on the existence of the particular form, but also to reveal some misleading ‘tendencies’ or implicit ‘principles’ inherent to the Esquirolian nosology, in order to shine a new light on the conceptual apprehension of madness. Falret emphasized the importance of thorough clinical observations and the perspective of the whole patient, rejecting the partial attention given to isolated symptoms, and in this respect his work represents a turning point away from the more traditional alienism.