We cannot contemplate men like Bacon, Galileo, and Kepler, for example, without feeling how auspicious the precession of such minds must have been to the development of the genius of Newton[1]. Newton was born the same year that Galileo died. There is something very interesting and significant too in the peculiar powers of Kepler. Prolific in suggestion, great in mathematical ability, elaborate in analysis, and singularly truthful in spirit, Kepler exemplified two things. These, though very distinct from each other, were both equally instructive; both alike suggestive of the link he represented in the chain of progress. In the laws he discovered, he showed the harvest seldom withheld from the earnest search for truth; but the enormous labour of the mode in which he conducted his researches, as well as the limits prescribed to his discoveries, exemplify the evils which, even in a man of the greatest power, result from proceeding too much on hypothesis. Now it is interesting to remember that this was coincident with the dawning of that glorious light, the Inductive philosophy of Bacon, and shortly succeeded by the splendid generalization of Newton.
In like manner, if we think of the discoveries of Sir Humphrey Davy—their nature and relations to physiology as well as chemistry,—we see how much there might have been that was preparatory, and, to a mind like Davy's, suggestive, in the investigations of preceding and contemporaneous philosophers. Priestly had discovered oxygen gas; Galvani and Volta had shown those remarkable phenomena which constitute that important branch of knowledge, "Voltaic electricity;" Berzelius had effected the decomposition of certain salts by the Voltaic pile; and Lavoisier had even predicted as probable what Davy was destined to demonstrate[3]
In medical science, few things have been more talked of than the discovery of the circulation of the blood. Now it is curious to observe that every fact essential to the demonstration of it had been made out by previous investigators[4] but no one had deduced from them the discovery of the circulation until Harvey, although it was a conclusion scarcely more important than obvious.
There is surely something very encouraging in the reflection, that the advance of knowledge thus results from the accumulated labours of successive minds. It suggests, that however unequally the honours may appear to be distributed—however humble, in our eyes, the function of those who unconsciously prepare the way to great discoveries,—still it may involve a duty no less important than the more lofty mission of enunciating them. The importance of a man's mission can never be estimated by human judgment. We can never know the mission; still less its relations to the power, or the temptations by which that power has been assailed. The most humble may here often approach as nearly to his duty, as the most gifted may have fallen short of it. Our faculties cannot penetrate the matter. We often see men placed in positions for which they appear wholly unfitted—men who seem to be bars to that progress which we should fancy it their duty to promote. Again, we observe that almost all great discoveries have to encounter opposition, persecution, obloquy, or derision; and when they are established, a host of claimants rise up to dispute the property with the rightful owner. A man who is in earnest cares little for these things. They may at times discourage and disappoint him; but they only strengthen his faith, that a day will come when an unerring justice will accord to every useful improvement its proper place and distinction.
Humanly speaking, we naturally ascribe discoveries to those who have practically demonstrated them; but when we examine all the clues which have been furnished by previous observers, we frequently have misgivings as to the justice of our decisions. In our admiration of the successful labour of the recent inquirer, we sometimes forget the patient industry of the early pioneer. With regard to those laws which govern the human body, we cannot suppose that the development of them can be destined to progress on any plan less determined than other branches of human inquiry. But in all laws of nature we know that there are interferences which, until explained, serve to obscure or altogether to conceal the law from our view.
In relation to the Physiological laws, these interferences are very numerous. 1st. Many are furnished by the physical laws; many more arise from the connection of the physiological with the moral laws, and especially from the abuse of (a responsible) volition. These interferences, however, when their nature is clearly developed, beautifully illustrate the laws they at first obscured; for the common characters of subjects, in which the law is usually exemplified, are brought out into higher relief by the very diversities in the midst of which they occur. The progress of mankind towards a popular familiarity with this fact, is necessarily slow; but still we think it plainly perceptible. An individual life, indeed, however distinguished, represents a mere point in time; it affords little scope for considering, much less for estimating, as they occur, the true meaning of various events, which nevertheless ultimately prove to have had important influence on the progress of knowledge.
These are world-wide things, which we must survey as the geologist does the facts concerning which he inquires. We must endeavour to combine, in one view, facts over which long periods of time may have rolled away, with such as are still passing around us. This will frequently suggest designs and relations altogether unobservable by the mere abstract inquirer. In the course of the following pages, a further opportunity may occur for a few remarks on such views; the elaborate discussion of the subject would be altogether beyond our present objects.
It will be our endeavour to point out the position occupied by Abernethy, in that (as we trust) gradually dawning science, to a particular phase of which our object and our limits will alike restrict our attention. We mean that period when Surgery, having approached to something like a zenith as a mere practical art, began to exhibit, by slow and almost imperceptible degrees, some faint characters of science—a shadowy commencement of a metamorphose, which we believe promises to convert (though we fear at a period yet distant) a monstrous hybrid of mystery and conjecture into the symmetrical beauty of an Inductive science—a science based on axioms and laws which are constantly exerting a powerful influence on the social progress and the health of nations.
In considering Hunter and Abernethy, we shall see not only a remarkable adaptation for the tasks in which they were respectively engaged, but also how the peculiar defects of the one were supplied by the characteristic excellences of the other. We shall see that they cooperated in laying open clear and definite objects; and that, though their modes of inquiry were far from fulfilling the requisitions of an Inductive science, they were eminently calculated to suggest the convenience, and impress the necessity of it.
We no sooner begin to inquire with clear and definite purpose, than we are led to the means necessary for the attainment of it.