CHAPTER IV.

MEDICINE.

pro

THE profession, whose department of knowledge now comes under consideration, occupy an immense field of science, and, by their number, constitute a large class of the learned world. In addition to the incentives of philanthropy and fame, which equally actuate the exertions of others, physicians are combined into a corps of observers and practical inquirers by the nature of the employment and duties they assume, and by the connection which the usages of society establish between their duties and emolument. In discharging their fessional labours, they incessantly find observations. and facts obtruded on their attention; and by combining these into hypotheses, theories and systems, they only indulge a favourite and almost irresistible propensity of the human mind. Hence arises the vast mass of writings which fill medical libraries, constantly accumulating, and too numerous, extensive and diversified to come within the comprehension of an individual inquirer. Whoever duly considers these things will perceive the necessity of resting satisfied on this occasion with a transient retrospect. To attempt any minuteness of detail would be to travel far beyond the limits assigned to this work, and to engross the pages which are destined to the examination of other subjects. All that can be aimed at is briefly to notice some of

D

the more important revolutions and improvements which distinguish the last age, and to commemorate a few of the illustrious names to whom the praise of them is chiefly due.'

Within the period assigned for this review, the state of medicine has been essentially changed, and has acquired a degree of extent, popular dissemination, and practical usefulness, unknown to preceding ages. The improvements in natural history and chemistry, mentioned in the preceding chapters, have greatly contributed to this extension, and may be considered as inexhaustible sources of materials calculated for a similar extension in future times. The more enlarged intercourse of mankind, the greater facility of communicating opinions and discoveries from one region to another, and the progress of commercial arrangements, by which the choicest productions of one country become the property of every other, may also be enumerated among the causes of this advancement.

In no period so much as in the last century, and in no science more than that which now engages the reader's attention, have the advantages been exhibited which arise from Lord BACON's plan of pursuing knowledge by observation, experiment, analysis and induction. Every department of medicine bears witness of the efficacy of this process to remove the rubbish of prejudice and error, to present truth in a simple form, and to establish it upon a legitimate foundation. A more precise, rigid and logical mode of philosophising has been generally substituted for the wild and visionary hypotheses which disgraced the science of the preceding centuries.

For many of the names, facts, and details included in this chapter, the. author is indebted to a medical friend.

To understand the history of medicine at any period, it is necessary to trace the progress and mark the affinities of all the sciences which are contemporarily cultivated. Not only the reign of fashion, but the peculiar acquirements and taste of individuals are often to be considered in an estimate of their medical principles. "La Philosophie," says M. D'ALEMBert, "La Philosophie prend, pour "ainsi dire, la teinture des esprits ou elle se trouve. "Chez un metaphysicien, elle est ordinairement "toute systematique; chez un géomètre, elle est "souvent toute de calcul." The application of this remark, if possible, is more eminently verified in respect to medicine than to philosophy in general. This propensity of the human mind is productive both of good and ill effects. If it be easy to show examples of injury sustained by the precipitancy of mathematicians, chemists and metaphysicians, in applying their doctrines to medical science, which cannot indeed be reasonably doubted; it is equally easy to prove that great benefit has arisen from such applications.

But notwithstanding the advantages and improvements which the eighteenth century has bestowed upon medicine, it must still be admitted that its progress has never equalled the sanguine expectations formed by many. Although nearly coeval with the existence of mankind, and demanding attention in every stage and condition of human life, the art of healing maintains a struggle with difficulties at every step. Like all other knowledge derived from observation and experience, that of medicine, though continually progressive, is subject to perpetual revolution. This tardiness, therefore, in the career of improvement, which all must admit and deplore, will excite no surprize in such as consider the mystery which still envelopes the principle of life, the labour of watch

ing the operations of nature, the numberless fallacies which attend the endeavour to discriminate truth from falsehood, and the smallness of the stock of genuine and undisputed facts which all the observation and wisdom of ages have been able hitherto to collect.

There is no species of knowledge, relating to affairs merely human, which more indispensably requires steadiness of principles and harmony of opinion than that now under consideration. There is none in which speculation and action are more intimately related, where error is of more immediate and fatal consequence, or where a fluctuation of the mind between opposite decisions is attended with more embarrassment and distress. Yet medicine abounds with schisms and controversies; and in the present imperfect state of knowledge, to hold doctrines and adopt practices beset with the fewest errors constitutes the highest attainment within the reach of the human mind.

ANATOMY.

This subject was pursued with so much diligence soon after the restoration of learning in the fifteenth and through the two succeeding centuries, as to leave less than might be expected for the investigation of modern anatomists. LEONARDO DA VINCI made great progress in anatomical studies towards the close of the fifteenth century." In the sixteenth century flourished the immortal VESALIUS, the founder of rational and systematic anatomy, whose works afford surprising proofs of

This was the first man who introduced the practice of making anato mical drawings. These drawings, preserved in a British collection, excite astonishment at the depth and accuracy of his knowledge,

After him

laborious and successful dissection. appeared SYLVIUS in France, COLUMBUS, FALLOPIUS and EUSTACHIUS, in Italy; whose discoveries and improvements were so numerous as to give a deep impression of the zeal and enthusiasm with which the knowledge of the structure of the human body was cultivated at that early period.

Soon after the time of the last mentioned writers the study of anatomy was gradually diffused over all Europe. The principal impediment to its progress, in that age, was the difficulty of obtaining human subjects for dissection; the want of which frequently made it necessary to dissect the bodies of brutes.

With the dawn of the seventeenth century new lights were shed upon anatomical inquiries from every quarter. At this time FABRICIUS AB AquaPENDENTE, an eminent Italian teacher, published his account of the valves in the veins, which evidently affected the established doctrine of all former ages, that the veins carried the blood from the liver for nourishment to all parts of the body. The detection of these valves may also justly be supposed to have laid the foundation of the discovery of the circulation of the blood.

For Dr. HARVEY, the pupil of FABRICIUS, was reserved, soon afterwards, the noble discovery of the circulation of the blood. This was by far a more important step in the knowledge of animal bodies than had ever been made before, and gave a new spring to anatomical inquiries. In a few years after HARVEY's discovery, ASELLIUS, an Italian physician, found out the lacteals, or vessels which carry the chyle from the intestines. And about the middle of the seventeenth century PECQUET, in France, was so fortunate as to discover the thoracic duct, or common trunk of all the lacteals, which conveys the chyle into the subclavian vein,