In conducting the treatment of diseases of the digestive organs, whatever organ we may desire to influence, either by inducing tranquillity of the nervous system, or by the selection of food appropriate to the actual condition of the organ specially affected, the stomach is necessarily a primary consideration. The reasons for this are sufficiently obvious, but have not perhaps been always adequately regarded. Digestion is, on the whole, a manufacture, so to speak, of a raw material (food) into a fluid (blood), which is to be absolutely adapted to purposes for which it is designed. This is effected not by one, but by several organs, which each produce their respective changes in the materials submitted to them. If we desire, therefore, to adapt the work to any organ which is engaged in this process, however remote it may be from the stomach, which, with the teeth and other auxiliaries, execute the _first_ process in the manufacture, it is quite clear that we must begin with the _first process_ to which we subject the said raw material or food. Say that in a machine for the manufacture of cloth the spinning apparatus were out of order, we must begin by giving out a less quantity of wool to the carding machine, or whatever represented the first process; because, having once delivered the wrong quantity or quality, we have no means of recalling it, and we should only still further derange the defective machinery. So in the body; the liver, kidney, and other organs, not excepting the lungs and skin; their work must all bear relation to the quantity or quality of raw material, whether their function be the manufacture of the new product, or the rejection of that which is useless. So that supposing there were no other reason, no other than this mechanical relation (which is very far from the real state of the case), still we must _de facto_ begin with the stomach, even where we entertain _no idea of any_ special derangement of that organ. The stomach, however, is very important in another sense, and has a power of indicating the necessity of attention to those points which I have endeavoured to illustrate by the homely similitude of a manufacture.