We have treated the brain, not as a mass of organs radiating from the medulla oblongata as their real center, but as two cerebral masses, each of which is developed around the great ventricle. We have freely applied an easy psychical and physiological nomenclature to the functions of its organs, knowing that there is no arbitrary division of them by specific number, for the cerebrum, in an anatomical sense, is a single organ. The doctrine of cerebral unity is true, and the doctrine of its plurality of function is true also. Whatever effect an organ produces when acting in entire predominance, is regarded as the function of that organ and is expressed by that name. Although our names and divisions are arbitrary and designed for convenience, yet they facilitate our consideration of the psychical, and their corresponding physiological functions. Every cerebral manifestation denotes a _psychical_ organ, and in proportion as these acts are transmitted to the body it becomes a _physiological_ organ. We have ventured to repeat this proposition for the sake of the non-professional reader, that he may be able to distinguish between' the two results of the manifestation of one organ. The transmission of the influence of the brain into the body enables the former to act physiologically, whereas, if its action were confined within the cranium, it would only be psychical. In the language of Prof. J.R. Buchanan, "every organ, therefore, has its mental and corporeal, its psychological and physiological functions--both usually manifested together--_either capable of assuming the predominance_." We have already seen to what degree the _Will_ operates upon the organism, or how "the soul imparts special energy to single organs, so that they perform their functions with more than usual efficiency," and thus resist the solicitations of morbific agents. Doubtless our best thoughts are deeply tinged by the healthful or diseased conditions of such organs as the stomach, the lungs, the heart, or even the muscular or circulatory systems, and these impressions, when carried to the sensorium, are reflected by the thoughts, for reflex action is the third class of functions, assigned to the cerebrum. These reflex actions are either hygienic and remedial, or morbid and pernicious. Hence, it is philosophical not only to interpret the thoughts as physiological and pathological indications, but to consider the cerebrum as exerting real hygienic and remedial forces, capable of producing salutary reparative, and restorative effects. When a boiler carries more steam than can be advantageously employed, it is subjected to unnecessary and injurious strain, and is weakened thereby; so, when the body is overtasked by excessive pressure of the volitive faculties, it is prematurely enfeebled and broken down. There are many individuals who need to make use of some sort of safety valve to let off the surplus of their inordinate ambition; they need some kind of patent brake to slacken