Mecum." Here it says that disease exists "when any structure of the body is changed not by violence, and when function is too active, torpid, or altered." Now, on this view, we should get some curious additions to the list of diseases. I will mention only one as a structure of the body changed not becomes a disease. Take next Dr. Russell Reynolds's definition; according to it a disease is any condition of the organism which limits life in either its powers, enjoyments, or duration. On this view, very oddly, the non-development of the testes is a disease, as by it the powers at least of life are limited, and we should thus all be little patients until 15, or thereabouts.

DELIVERED AT

Guy's Hospital

By W. MOXON, M.D., F.R.C.P.,

Assistant-Physician and Pathologist to the Hospital.

LECTURE I.

CONSIDERATION OF THE SUBJECT. GENTLEMEN,-My first duty is to endeavour to make quite clear to you what pathology is. This may seem to you to be an easy task enough. But we shall soon find out its difficulty, and in trying to solve the difficulty we must undertake some very general and wide considerations.

The literal meaning of the word pathology you will at once see is too wide. If we take it to mean the science of disease, its range then embraces the symptoms of diseases, the changes in the body produced by them, and their causes; and these branches of so comprehensive a conception of pathology would diverge beyond our compass.

We must divest this wide motion of pathology of some more extrinsic members, and limit the science of disease to such aspects of the study of diseases as are not taken up by other branches of Medical inquiry, such as nosology, morbid anatomy, and etiology.

But plainly it is needful for us, before thus dealing boldly with the science of disease, and cutting it up into segments, to be sure we know what it is that we are about to handle so freely. The science of disease. What is a disease? This is the first question. It seems easy, but it proves to be one of those things which everybody knows and nobody can say.

The doctors have not so powerful a voice in determining the meaning of the word as the general public have. They know what they mean by it. They mean their aches, and pains, and dangers. And they mean you to mean the things they want you to cure, and for their side of the matter that is quite enough of a notion. But for ours who have to meet and combat these diseases, it becomes necessary to get a clear view of our antagonists, that we may if possible know where and how to confront them.

To urge you further to this inquiry I would get you to reflect in this way. Most men who deal with things want to use them and alter them, but all the while to preserve them. We, on the other hand, who deal with diseases, want to destroy them. But to use a thing wants less knowledge of it than is required to destroy it; to use it, you take it as it is for granted; to destroy it, you must have some acquaintance with the plan of its maintenance, always supposing that you cannot mechanically crush it, or cut it to pieces.

To understand the difficulty in clearly grasping the general notion of what a disease is, we must see that diseases are not things, but changes in a thing. Those sciences which, like chemistry or zoology, deal with material substances, must always have a vast advantage over pathology. The thing which the chemist considers, lies for every one to handle. The pathologist very imperfectly watches the changes that make up a disease, and as he is watching they disappear, and he cannot gather them all together, to get once and decisively a completed idea of them. And hence he is in danger of restricting his attention in his study too much to the tangible products of diseases, dwelling on their characters as if they were things precious in themselves; whereas it is not as things but as changes that the products of disease are to be viewed. I repeat it, we must avoid mineralogising over tumours and tubercles, as if they were the ores of valuable metals. The process of their production, that is our concern.

Now, seeing that any disagreeable change in one's frame or its actions will be popularly called a disease, and that the popular voice determines for itself, and will have this for its meaning of disease, let us try and make a more accurate and scientific definition. If we say "disease is bad health," that only stands our difficulty on the other leg as obdurate as ever; For then we have to answer the question, " What is health?" and that is, perhaps, worse.

I will take two definitions out of text-books, and we shall see by their little success how difficult it is to define disease. First, we will take the view given in Dr. Guy's "Hooper's Vade

VOL. IL 1870. No. 1044.

I will then try and make another definition. We will say that a disease is anything wrong in the life of all or part of the body--let me underline life, though you may think it makes the definition rather vague. I will lay stress upon it, because, if we get over the first apparent vagueness of this view of disease, and stand to see disease as altered life, then we shall, I think, more easily get over the first stumbling block offered in our path to the more detailed consideration of disease-I mean the old and universal, and, in some sense or other, always necessary, division of diseases into structural and functionalfor if we see disease as altered life, then whatever the relations of structure and function are in the history of life, such will be the relations of structure and function in the history of disease. If we can clearly comprehend how structure stands related to function in the several activities of our different organs, then we can apprehend the relation of them in the disorders of those organs.

Now, it is a very important and a very interesting inquiry that asks what is the relation of structure to function in vital phenomena. And in the answer we shall early find that the relation of structure to function in the tissues depends on whether it is direct, arising in the tissue, or indirect, depending on the act of some other part of the frame.

We should first beware of the danger of thinking things in nature to be separate in the same way as they are in our thoughts.

Life, we say, consists of two things: the maintenance of a form and the performance of certain functions, and we cannot help at first conceiving these as very distinct, because the form of all machineries such as we see the body to be is so very different a thing from the work of those machineries.

But Nature works in a very different way to the way we work; indeed, she works in a very opposite way. We in our manufactures take separate things and put them together to make one. Nature in her processes takes a thing that is all of

a kind, homogeneous, and makes the one develop into two or more. We put separate things together; Nature separates things that rise together. And hence the very framework of our language is calculated to mislead us when we apply it to describe the processes of nature. For instance, we say, the biceps is inserted upon a certain spot of the radius; but inserted, a word that implies a bygone act of insertion, is not applicable, for there never was such an act. The biceps and the radius grew as they are, and to say that one is inserted upon the other is to make a directly wrong statement which, however, we cannot well avoid, but which we cannot too clearly guard against, lest it induce us to overlook the true nature of vital acts, and to look on living bodies as if they were altogether comparable to manufactured machineries.

The distinction in our bodies of the machine and its work is very well up to a certain point. The mechanical functions of support or of movement in our mechanism are as simply the produce of the levers and powers as are the movements of the cranks and wheels of a steam-engine, and so in dealing with the action of the heart or of the limbs any difficulty about structure and function seems absurd.

But then these mechanical structures and functions are themselves only secondary things, and they arise out of vital operations of a kind that more nearly concern pathology. A structure, like muscle, tendon, or bone, which takes its function from nerve or cther tissue, may certainly show functional imperfection through the failure of its nerve, and so you get functional paralysis of a sound limb, etc. But when we come to tissues whose functions arise in themselves, then we find the structure of the part and its function so connected that we do not easily discriminate between them. The production of the gland cell and of its secretion is but one continuous act; so the production of a nerve-cell and of its powers of radiation; so the production of a muscle-fibre and of its powers of contraction. We have to learn to see in the maintenance of each tissueelement not a set and permanent product, such a thing as we ourselves make, but a shape taken by a stream of matter which,