One of the first fruits of the new method of study introduced by Pinel was a more philosophical notion of the nature of disease. The various diseases that afflict mankind had been regarded as so many different entities that could almost be handled, and many attempts to define and measure them exactly are on record. They came to be regarded somewhat as personal foes, to be combated and overcome by the superior prowess of the physician. It was not until such views were abandoned, and insanity, as well as every other disease, was considered as an abnormal action or condition, that true progress could be expected. One of the results of inquiry into the nature of insanity, starting from this point, has been a growing conviction that it implies defect and imperfection, as well as casual disorder. Attention is now directed less to occasional and exoteric incidents, and more to conditions which inhere in the original economy of the brain. We are sometimes required to look beyond the individual, and beyond the nervous system even, if we would discover the primordial movement which, having passed through one or two generations, finally culminates in actual disease. We say, in popular phrase, that the cause of insanity in this person was disappointed love, or reverse of fortune, and in that, a fever, or a translation of disease; the popular voice finds an echo in the records of the profession, and it all passes for very good philosophy. Now, the more we learn, the more reason have we to believe that the amount of truth in the common statistics respecting the causes of insanity bears but a very small proportion to the amount of error. That such things as those just mentioned are often deeply concerned in the production of insanity cannot be doubted, but their agency is small in comparison with those which exist in the original constitution of the patient, and are derived, in greater or less degree, from progenitors. We would not say that insanity has never occurred in a person whose brain was not vitiated by hereditary morbid tendencies, but we do say that the proportion of such cases is exceedingly small. All the seeming efficiency of the so-called "causes of insanity" requires that preparation which is produced by the deteriorating influences of progenitors, and without which they would be utterly powerless. Let us consider this matter a little more closely by the light which modern inquiry sheds upon it.