Under the intellectual organs, I class, first, the organs of sense, where impressions take place; second, the brain or organ of judgment, where these excite ideas; and, third, the nerves, where volition results from the last. This is a natural arrangement of the anatomy of animals, and its peculiar simplicity is illustrated by its involving, in application, that of minerals and vegetables, and by its being capable of instant adaption to physiological science. In order to arrange animal physiology, it is only necessary to substitute the term “functions” for “organs;” and that science will likewise involve, in application, the physiology of mineral and vegetable bodies, and be, in its turn, capable of instant adaption to medical science. Thus, the functions also are divided into mechanical, vital and intellectual. The mechanical functions are subdivided into that of support, that of connection and that of loco-motion. The vital functions are divided into that of absorption, that of circulation and that of secretion. The intellectual functions are divided into that of sensation, that of mental operation and that of volition. In order to arrange medical science, for the term “healthy functions,” the subject of physiology, it is only necessary to substitute the term, “diseased functions.” The classes of disease are, therefore, like those of anatomy and physiology, three, namely, diseases of the mechanical or loco-motive functions, diseases of the vital functions, and diseases of the intellectual functions. The orders of the first class, as affecting the functions of the bones, the ligaments and the muscles, are three, viz. diseases of support, diseases of connection, and diseases of loco-motion. Those of the second class, as affecting the functions of the absorbent, circulating and secreting vessels, are likewise three, viz. diseases of absorption, diseases of circulation and diseases of secretion. Those of the third class, as affecting the functions of the organs of sense, of the brain and of the nerves, are also three, viz. diseases of impression, diseases of judgment and diseases of volition. The genera, under each order, consist of diminished, irregular and increased function. This arrangement of disease likewise involves in application, that of minerals (if we choose to maintain the analogy and to give that term to mere injury of structure) and of vegetables, as well as animals. The first have what may be termed diseases of mechanical structure; the second have diseases of mechanical and vital functions; whilst the third have diseases of mechanical, vital and intellectual functions; corresponding with the observation that animals exist, vegetables exist and live, and animals exist, live and think. Precisely in the same way, would I class the articles of the materia medica; first, as operating upon the mechanical, vital or intellectual organs, and then as either increasing, rendering irregular, or diminishing their action.