When the American Psychiatric Association first approached the problem of formulating a definite scheme for the collection of statistical data relating to mental diseases it was immediately confronted with the necessity of adopting an official classification of psychoses purely for purposes of uniformity. This undertaking, which suggested no difficulties at the outset, led to all kinds of unexpected complications and embarrassments. Classifications of "insanity" are almost as old as the terms mania and melancholia and have been given a grossly exaggerated importance by the space which for so many years has been devoted to a consideration of this subject in textbooks. This, if nothing else, appears to have been demonstrated quite clearly by the discussions of the last few years. A review of the literature of psychiatry shows that attempts to classify the psychoses date back almost to the beginning of medical history. Hippocrates is said to have recognized three forms of mental disorders—mania, melancholia and dementia, although there is some question as to his having used those terms in accordance with their present significance. Celsus[130] also described three forms of insanity. The first, which was accompanied by febrile symptoms, he termed phrenitis. The second was characterized by sadness and caused by black bile. The third was accompanied in some cases by false images, while in others the whole mind or judgment was impaired. The Roman law divided the dementes or mad into two classes, the excited or violent (furiosi) and those deficient in intellect (menti capti). Aretaeus[131] discussed mania, melancholia and dementia, apparently regarding them as all manifestations of some one disease process. Melancholia, he said, "does not affect all the faculties of the mind; the patients are sad and dismayed; they are without fever." He described it as only an initial stage of mania. Caelius Aurelianus[132] did not regard melancholia as a form of insanity, "from which disease it differs in that the stomach chiefly suffers, while in Madness it is the head." Galen in his writings referred to amentia or dementia, imbecility, mania and melancholia.