General paralysis is common in our large cities, and assumes so many disguises that it is necessary to be ever on the alert for it. About a third of the male admissions to asylums between the ages of thirty-five and fifty suffer from it, and the possibility of its presence should always be remembered in the case of a man of this age presenting mental symptoms. Such men are usually the heads of families, and occupy positions of responsibility, for as a rule those who suffer from general paralysis are no weaklings. The social troubles and inconvenience produced by the occurrence of adolescent or senile insanity, bad as they may seem, are therefore trivial compared with those produced by a disease such as this, which attacks the bread-winner of a family and the head of a business in the prime of his life.

Joseph Sheridan Le Fanu (1814-1873) is another literary Dubliner. Having studied law at Trinity College, he became a journalist and author, famous for both his sensationalist novels and his supernatural tales. For In a Glass Darkly Le Fanu used a technique common in gothic fiction by having a narrator/editor who presents past documents, in this instance of mysterious medical case histories from the papers of the nowdeceased Dr Hesselius. The latter is a European ‘metaphysical physician’ with Swedenborgian leanings who likes to investigate curious psychological phenomena. He considerably resembles the later Professor Van Helsing from Bram Stoker's Dracula.