To the medical philosopher, nothing can be more deeply interesting than to trace the reciprocity of action existing between different mental conditions, and affections of particular organs. Thus the passion of fear, when excited, has a sensible influence on the action of the heart; and when the disease of this organ takes place independently of any mental agitation, the passion of fear is powerfully roused. Anger affects the liver and confines the bowels, and frequently gives rise to an attack of jaundice; and in hepatic and intestinal disease, how irritable the temper is! Hope, or the anticipation of pleasure, affects the respiration; and how often do we see patients, in the last stage of pulmonary disease, entertaining sanguine expectations of recovery to the very last! As the passions exercise so despotic a tyranny over the physical economy, it is natural to expect that the crime of suicide should often be traced to the influence of mental causes. In many cases, it is difficult to discover whether the brain, the seat of the passions, be primarily or secondarily affected. Often the cause of irritation is situated at some distance from the cerebral organ; but when the fountain-head of the nervous system becomes deranged, it will react on the bodily functions, and produce serious disease long after the original cause of excitement is removed. It is not our intention to attempt to explain the _modus operandi_ of mental causes in the production of the suicidal disposition. That such effects result from an undue excitement of the mind cannot for one moment be questioned. Independently of mental perturbation giving rise to maniacal suicide, there are certain conditions of mind, dependent upon acquired or hereditary disposition, or arising from a defective expansion of the intellectual faculties, which originate the desire for self-destruction. These states will all be alluded to in the course of the present inquiry. Some idea of the influence of certain mental states on the body will be obtained by an examination of the various tables which have been published, in this and other countries, respecting the causes of suicide, as far as they could be ascertained. The following suicides were committed in London, between the years 1770 and 1830:[19]— _Indication of Causes._ _Men._ _Women._