That conjectures so gratuitous, and so utterly incompatible with the structure and functions of the animal frame, should at such distant periods of the world, under such different conditions of society, and in such different states of science so entirely possess and satisfy the minds of three of the most extraordinary men that ever illustrated or extended any department of science, will appear the less wonderful when we consider that the doctrines relative to fever which displaced and succeeded these, originated in precisely the same error, and vary in their aspect only in conformity to the progressive advancement of general science. When the structure of the animal body became more generally studied; when the functions performed by its different organs became better understood; when the morbid actions constituting or resulting from the derangement of these functions became more closely investigated, the influence of the nervous system and the effects of vascular action, began to form the subjects of investigation, and from this period the attention of physicians was fixed less upon the fluid than the solid parts of the frame. The properties and motions of the fluids were now clearly seen to be dependent upon the action of the containing solids, and the action of the solids to be under the influence and control of certain laws peculiar to life. Disease, studied under this juster view of the animal economy, immediately assumed a new aspect, and theories arose so much more consonant to the known operations of the living body, so much more explicit in their language and intelligible in their nature, that the ancient doctrines were at once exploded, and the very terms in which they were expressed became suddenly, though, as it now appears, only for a short time obsolete.