and the Task-works confessedly of great intellectual power, and adorned with every beauty of sentiment and description. Who can calculate the amount of good to which they have contributed, in reaching the heart and conscience, because they first swayed the understanding, and captivated the taste of their readers. In a lower degree, the Rambler of Johnson supplies us with an example in point. Its influence, perhaps, is not directly or positively religious, at least not evangelically so; yet as restraining from vice, promoting morality, checking the progress of unbelief, and fortifying the outworks of christianity, this production shows the power of transcendent talent, united with great reverence for religion, if we may not say, with a participation of its spiritual influences. What untold good, from generation to generation, has not been effected by the learning and taste of Watts, united with his love to God and man, in his religious lyrical poetry! When will the hymn,

"Come, let us join our cheerful songs,"

or this of Fawcett,

"Blest be the tie that binds,"

or an hundred others of nearly equal merit, be forgotten by the church of God? And to mention one or two others, whose instrumentality in doing good, is not to be measured by the number of their couplets-how long will not christians in their worshiping assemblies, or by their fire-sides, express their gratitude for the death of Christ in Cowper's lines

"There is a fountain filled with blood,"

Or who shall say that Heber's delightful missionary hymn, shall cease to animate the zeal of the pious in the conversion of the world, till that enterprise itself shall be accomplished? In these, and a thousand other instances, cultivated mind has concurred with religion in the production of works in which the amount of spiritual benefit already experienced, can be estimated only in eternity. But for the junction of these attributes, piety would have been essentially circumscribed in its influence; nor would it have been a matter of regret, had knowledge also been similarly circumscribed. The observations above offered on their mutual combined influence, will apply in an emphatic manner to the christian ministry. The advantage thence derived, in this department of a most important human agency, must be too obvious to be overlooked. But though our remarks have been elicited in view of an example presented by an individual minister of religion, we have considered the subject thus generally, without identifying it with the sacred profession, the rather because its connection with this profession has been recently developed in our pages, and because it is in itself susceptible of a wider range of application.

ART. IV.-ELEMENTS OF MEDICAL LOGIC.

Elements of Medical Logic. BY SIR GILBERT BLANE, BART. etc.

We have placed the title of this work at the head of the present article, not with any design of examining into its merits, but for the sake of calling the attention of our readers to the general subject which it embraces, we mean the mode of reasoning in medicine, as distinguished from other branches of science. The subject is one of deep interest, not to the physician merely, but to enlightened men of every class. On clergymen especially, it has claims of a peculiar nature, not only because they have great influence in the selection and support of medical practitioners among the people of their charge, but particularly because in periods of severe and prevailing sickness, their judgment respecting the mode of treatment adopted by physicians, has a powerful effect to calm or agitate the public mind.

Such periods have existed, and may soon arrive again in this country. The spasmodic cholera, after traversing the eastern continent in every direction, from the Chinese Sea to the suores of the Baltic and the German Ocean, and laying waste three millions of our race, has made its appearance in the British Islands. How soon this frightful malady may be in the midst of us, it is impossible for any one to say. The public mind is already most fearfully awakened to the probability of such an event; and all the information which can be obtained respecting the nature and progress of this afflicting scourge of the human race, is sought with avidity and listened to with the deepest interest. Under these circumstances, it becomes doubly important that the public should be well informed on the principles of reasoning which apply to medical subjects. We shall therefore call the attention of our readers for a few moments to this topic.

The practice of medicine is proverbially uncertain and truly difficult. The causes of this fact are various, and of a peculiar kind. It is extremely complicated, and to practice it intelligently, and with any certainty, requires the intent consideration of a great variety of circumstances and phenomena. We have a delicate piece of animal mechanism to deal with, whose movements even in health are of a very compound and intricate character, which are deranged or perverted by the most trifling causes, some of which are invisible to the eye, or not cognizable by any of the The body is the subject of almost numberless diseases, each assuming a countless variety of shapes, and producing a multiplicity of disorderly and anomalous actions, with difficulty traced

senses.

out and detected in their shadowy forms, and seen in their true character. Besides these causes of derangement and complexity which require the careful attention of the physician, the animal system is surrounded by an inanimate world, to the laws of which it is, as matter, ultimately subject, and with which it has to maintain a perpetual warfare. In this sense, life has been beautifully said to be a forced state. It has to maintain its existence in direct opposition to every material agent in nature, each of which seems enlisted in avowed hostility against its being. Though capable of resisting successfully all these external forces, it is still acted upon by them, and modified and molded and sometimes actually deranged by their influence. Now the physician must look upon all these things, and estimate their effects both in their simple and combined state, otherwise he cannot act intelligently. He must have capacity and discipline of mind, in order to enable him to take in at a single view many various and complex phenomena, to see all their bearings and relations and dependences, and to determine at a glance the precise influence of each and every circumstance in the general result.

The animal movements are all out of sight. They are carried on in those secret labyrinths of the system into which the eye cannot penetrate or the light enter. The knife will develope the composition and parts of the dead body, and their relative situation; but it will not lay open and expose to naked inspection the machinery of life. Life is in itself inscrutable; it escapes in the search for it. If we lay open the chest and bare the heart, its pulsations may be seen, and the vital current perceived circulating in its cavities; but these phenomena are only effects of the vital principle. We get no clue to the principle itself. The ultimate cause of the movements of the heart, as well in a healthy as diseased state, eludes inquiry; consequently the remedial agent which is capable of exerting a control over such movements can only be known by experiment. A priori reasoning can never lead to the knowledge of the action of any remedy upon the human system. The liver is an important organ, whose function is to secrete bile. It is liable to disease, and, as an effect, to disordered function. This organ cannot be examined in the living body, but in the dead subject, it exhibits traces of its previous state, such as inflamation, congestion, tubercles, etc.; but these appearances do not acquaint us with the cause, the particular nature and character of the disease; nor, independent of experimental knowledge which bears directly or indirectly upon the case, suggest to us the proper remedy, nor even the appropriate class of remedies. The effects of curative agents upon the body, is a distinct inquiry,

in which the knife has no concern. The qualities of each remedy, and its virtues in each sort of morbid action, are to be ascertained by reiterated trial. Reasoning from the nature of things, independent of experiment, could do no more in communicating this species of knowledge, than it could do in acquainting us with the fusibility of lead or tin previous to their being subjected to the influence of heat, and previous to its being known that any of the metals were fusible. Who could tell that calomel would purge, or salivate, or cure inflammation of the liver, before he had seen it produce these several effects? On what principle would a man argue the virtues of quinine in intermittent fever, previous to its actual administration in this species of disease? The essence of life and of disease, and the powers of medicine, then, cannot be known by dissection.

The rules laid down for the cultivation of natural philosophy, do not apply to medicine. The laws that govern the material world are fixed, uniform and universal. When they have been once ascertained, they may be safely taken as data in all our processes in reasoning. Our conclusions possess a sort of mathematical precision and certainty. Sir Isaac Newton assumed that similar causes produce similar effects, and vice versa, that similar effects imply similar causes. This was true in the sciences with which he was conversant, but it is not true in physic. The animal body is made of different materials (or rather materials in a different state of combination,) from the material world, and is ruled by laws of its own, unique in kind. Medical phenomena instead of being fixed, uniform and universal, are unstable, irregular and partial. Instead of that which is in general simple and plain, easy of access and investigation, we have that which is complex and intricate, inaccessible and difficult to investigate. Similar causes do not produce similar effects, but those which are very diverse.* For instance, a full meal of indigestible food will produce in one man vomiting, in another purging, in another asthma, in another head-ache, in another apoplexy, &c. Even in the same person, a great variety of effects will follow an error of this sort, at different times. The fact that similar effects do not argue by any necessity similar causes, may be illustrated in a like manner. Asthma may arise from unwholesome food, from fatigue, from impure air, from water in the chest, &c. Ap-. oplexy may be occasioned by heat, by mental or bodily excitement, by a blow on the head, by a heavy meal, by transferred gout or rheumatism, and by as many causes as there are agents

* Vide Dr. Calhoun's Introduction to Gregory's Practice of Physic, 1829.

which may act injuriously upon the human system. The same remedy, at different times and on different persons, will produce different effects: the same disease does not require the same remedy independent of time and person. There is no fixed and definite proportion between effects and their causes as in the m terial world. An increase or diminution of the latter is not followed by a corresponding increase or diminution in the former. The severity of the attack of dyspepsia by no means determines the intensity of the cause or causes which produced it. Thus we may see the difficulty of reasoning on medical subjects, and the unsatisfactory and often erroneous nature of our conclusions, when we undertake to introduce for our guide the received rules of natural philosophy. Often, consequently, when the most prompt and decided action is required, the best qualified are obliged to act on probabilities, and the ignorant at perfect random.

From the complexity and irregular and often fanciful succession of medical phenomena, (fanciful when compared with the regularity in the material world,) and from the multiplicity and uncertainty of their causes, and the manner in which they are combined and interlaced, as it were, with one another, the physician has a difficult and delicate part to act. The influential and controlling cause or causes in the production of any particular morbid state, is frequently so completely involved and concealed among such a multitude of other causes seemingly important, though truly unimportant, that the most learned and experienced and discriminating are often benighted, and sometimes led into error. An internal derangement may exist which may exert, primarily or secondarily, a controlling influence over the progress and termination of a disease, and still be so perfectly concealed as to elude notice, and even escape diligent inquiry. A deleterious external agent may be applied to the body, and occasion disorder, where it is almost impossible to discover its existence; or it may produce a train of symptoms where it is known to exist, of such an equivocal and anomalous character, as to leave such agent unsuspected; or such symptoms may become so modified or metamorphosed in process of time, that those peculiarities which served originally to connect them with their proper cause in the mind of the physician, have been finally lost. Malaria, or the miasm of marshes, the agent which produces that class of fevers called intermittent, may exist in sufficient quantities to produce its specific effects on the human constitution, and still remain undetected; or it may occasion complaints, under particular circumstances, of an irregular and very different character; or the disease which it naturally produces, may become so shaped, and disfigured, and disguised, in the lapse of time, that its oriVOL. IV.

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