The Court said: “The system pursued by the practitioner is immaterial. The law has nothing to do with particular systems. Their relative merit may become the subject of inquiry, when the skill or ability of a practitioner in any given case is to be passed upon as a matter of fact. But the law does not, and cannot, supply any positive rules for the interpretation of medical science. It is not one of those certain or exact sciences in which truths become established and fixed, but is essentially progressive in its nature, enlarging with the growth of human experience, and subject to those changes and revolutions incident to any branch of human inquiry, the laws of which are not fully ascertained. The labors of the anatomist, the physiologist, and the chemist have contributed an immense storehouse of facts; but the manner in which this knowledge is to be applied in the treatment and cure of diseases has been, and will probably continue to be, open to diversity of opinion. No one system of practice has been uniformly followed, but physicians from the days of Hippocrates have been divided into opposing sects and schools. The sects of the dogmatists and the empirics divided the ancient world for centuries, until the rise of the methodics, who, in their turn, gave way to innumerable sects. Theories of practice, believed to be infallible in one age, have been utterly rejected in another. For thirteen centuries Europe yielded to the authority of Galen. He was implicitly followed—his practice strictly pursued. Everything that seemed to conflict with his precepts was rejected; and yet, in the revolutions of medical opinion, the works of this undoubtedly great man were publicly burned by Paracelsus and his disciples; and for centuries following, the medical world was divided between the Galenists and the chemists, until a complete ascendency over both was obtained by the sect of the Vitalists. This state of things has been occasioned by the circumstance that medical practitioners have often been more given to the formation of theories upon the nature of disease and the mode of its treatment, than to that careful observation and patient accumulation of facts, by which, in other sciences, the phenomena of nature have been unravelled. I am far from undervaluing the great benefits conferred upon mankind by the study of medicine, and have no wish to minister to any vulgar prejudice against a useful and learned profession, but it is not to be overlooked that, as an art, it has been characterized, in a greater degree, by fluctuations of opinion as to its principles and the mode of its practice, than, perhaps, any other pursuit. That it has been distinguished by the constant promulgation and explosion of theories, that it has alternated between the advancement of new doctrines and the revival of old ones, and that its professors in every age have been noted for the tenacity with which they have clung to opinions,