was not the founder of any system, nor did he make any discovery. He simply used with supreme success the thoughts and discoveries of others; as soon as he ceased to live, his influence began therefore to decline; and before his generation had passed away, his star had waned before the genius of Cullen, who succeeded in fixing the attention of Europe, and who, in his turn, was soon to be displaced by others. Thus we are taught, for the thousandth time, the lesson we never shall learn, that the popular estimate of contemporaries does not decide the vitality of a reputation, but that lasting fame depends upon the answer to the question: What would the difference be in the world's history, had such a one never been born? If we apply this test to Boerhaave, we shall be forced to confess, that had his particular light been lost to the medical world by his adherence to his father's profession, it would not now be possible to recognize any diminution in the general radiance of the age. The works by which he is best known are, "Institutiones Medica in usus annuæ exercitationis domesticos," first published at Leyden in 1708, and "Aphorismi de cognoscendis et curandis Morbis in usum doctrinæ medicinæ," published in 1709. It is enough to show the estimate in which these works were held to say, that the great Haller published a commentary on the "Institutions" in seven quarto volumes, and that Van Sweten illustrated the Aphorisms" with a commentary which extended to five quarto volumes. Thus, on these two works of Boerhaave there are commentaries of twelve quarto volumes, by two of the most celebrated physicians of their age. The perusal of "The Institutions" confirms the impression of the character of Boerhaave, which one derives from the multitude of his successful enterprises-that he was, above everything, a man of rapid activity. He skims, with the swiftness of the swallow, the surface of all the subjects with which he deals, leaving nothing unnoticed, nothing unexplained, entirely satisfying the curiosity, without awakening any doubts. He is the Macaulay of medicine. We can perfectly understand how delightful it must have been to listen to a teacher who explained the structure and uses of all parts of the human frame; then described their various functions; passed from that to consider the laws of their healthy action; and concluded by giving a complete arrangement of diseases, and the modes of their cure. All this Boerhaave does with singular felicity of illustration, bringing equally his multifarious knowledge of history and his daily experience gained in practice, to bear on the topic on hand. He was an eclectic. "At present," he says, "physic may be learned without adhering to any particular sect, by rejecting everything that is offered without demonstration, and by collecting and retaining only what has been offered and approved to be real truth, both by the ancients and moderns."1 He strongly insists upon the importance of distinguishing a fact from a conjecture about it. "Thus, if any should say that the fixed salt of Tachenius is proper in the beginning of a dropsy, his assertion will be justified by experience; but if he proceeds to explain the manner in which it operates, it is very possible he may be altogether deceived." This is a hit at Hoffmann and the chemists. "What is demonstrated to us by our senses, cannot be disproved by any age The circulation of the blood will be as true and undeniable a thousand years hence as it is at the present time." In these and many similar passages we have the importance of facts or phenomena explicitly affirmed in the true Baconian spirit. Thus, in speaking of the Archæus of Van Helmont, he observes, "One might as well confess his ignorance of the cause of any action, as attribute it to 1 Vol. I., p. 43. 2 Ibid., p. 44. 3 Ibid., p. 48. "3 some imaginary and unknown being, of whose existence, nature, actions, and manner of operation, we have not the least knowledge or assurance." It is remarkable that Boerhaave, who was so thoroughly alive to the necessity of a rigid scrutiny of every explanation of a phenomenon, should have been so perfectly satisfied that the cause of animal heat was the attrition of the blood in its course of circulation. He seems impatient of contradiction in the matter, and utterly, almost contemptuously, rejects the notion of Lower and others, who derived the animal heat from the nitre to which it was exposed in the air received into the lungs-a conjecture much nearer the mark than that of Boerhaave. It is really amusing how he disposes of the obvious objection to his theory, that if animal heat depended upon the mechanical friction of the particles of the blood, we should have a similar effect in all hydraulic works. To this he replies, that blood is of a viscid and adhesive nature, and that it cannot be forced through the small vessels without producing great friction of its particles, and consequent heat. "It is, therefore, by the excess of force in the heart, that the animal heat is generated." 2 Yet, when Boerhaave taught this, he knew that Borelli had demonstrated that the sum of the cavities of the branches of an artery is always greater than that of the main trunk, so that the circulation is easier than would have been the case had they been of the same calibre; and moreover Boerhaave was perfectly aware that so far from the blood getting hotter as it recedes from the centre, it gets cooler, which, of course, it would not were his hypothesis correct. This is a good illustration of the fatal facility that is required for a popular teacher. Boerhaave undertook to explain the functions of the animal economy, and here was a most important one, which it was his business to explain. He was not 1 Vol. I., p. 310. 2 Vol. II., p. 216. there to excite doubts or to prosecute inquiries; he was there as a preacher to expound doctrines. Here then was an explanation which, on the whole, seemed the best, and was, therefore, to be accepted as the true one. Very rarely is the faculty of popular exposition united to an equal amount of that earnest inquisitiveness which makes the discoverer. The former is the expression of a satisfied, the latter of an unsatisfied, state of mind. Boerhaave was a man thoroughly satisfied with himself and everything about him. We might give innumerable illustrations of the superficial character of Boerhaave's method of dealing with the problems he had to explain, and the curious arguments he used to controvert his opponents. For example, he tells us that a celebrated Professor of his own University explained catalepsy by the supposition that it was caused by "a congelation of the animal spirits by a volatile, alkaline salt, in the same manner as alcohol and sal ammoniac do, upon mixture, form a solid body." Now, one might expect a disciple of Bacon to have dealt in a very summary way with such an bypothesis as this, by denying the existence of any such asserted cause, or the efficiency of such cause if actually existing. But Boerhaave meets the chemist on his own ground, and replies that the juice of the brain does not manifest any phlogistic quality, but extinguishes a flame when thrown upon it! How much he was influenced by the mechanical and chemical schools, is shown by his notion of the mode in which the nervous fluid is prepared. "The matter from whence the juices or spirits of the brain are prepared, is the viscid and tenacious serum of the blood, which, by passing through many degrees of attenuation, at length acquires the subtlety of a spirit, after its particles have been moulded or framed by passing frequently through the smallest series of vessels 1 Vol. II., par. 277. in the body; passing from blood into serum, from serum into lymph, from lymph of the first order into all the several orders; till at last, losing the nature of lymph, it acquires the subtle one of a spirit!" This is certainly spirit very much above proof. It is, after all, much the same notion, only worked out with more detail of chemical technicality, as that of Hoffmann,—and, indeed, of a great many more-that the spirit of man is a distillation of the body of man, and that the regions beyond our investigation are peopled with these volatile emanations, which retain the form of the human frame, but are without any of its other sensible properties-the ghost of Patroclus, as seen by Achilles, six thousand years ago, at the siege of Troy, and the ghost of the spirit-rapper as seen at Troy in the United States of America, in the present day. He speaks elsewhere approvingly of a notion, "that there is internally concealed a spirituous or nervous man, which governs the whole machine."1 What is this but the ghost? 2 We may give another striking illustration of the danger of being satisfied by an ingenious superficial explanation of a strange occurrence. He mentions a fish, resembling a skate, which, when touched, benumbs the hand, and explains it by the agitation of the skin, which is thrown into tremors by the subcutaneous muscle. "To me," he adds, "the whole affair seems to be no great difficulty; when a saw which is very tight and short is sharpened by a file, or a glass ball is sawed by a knife, or a short tense chord is scraped by the bow-all these operations give rise to such an intolerable shrieking noise as to set the teeth on edge. By the same reason, when the torpedo fish excites tremors in its muscles, similar tremors are excited in the nerves of the person who touches it."3 What was no 1 Vol. III., par. 507. 2 Boerhaave's 66 nervous man may be compared with Bacon's "body pneumatical," see p. 196. If this body pneumatical were liberated by |