To mark the improvement and advancement in the various branches of medical science; to compare the present with the past; to observe the unfolding growth, maturity, and decay of medical creeds; to discern the power of those master-minds, that, far beyond the ages in which they lived fore-shadowed the forth-coming discoveries that were to make other men immortal; to sigh over the incredulity of whole races, whose blind and dogmatical adherence to the theories of some prominent physiologist or anatomist--was at once silenced by the light of a new truth, suddenly and clearly promulgated by a single mind. To do all these things, was the labor of a whole life; volumes could be written in such investigation, and still thousands of facts be left untouched and forgotten, forever buried in the chaos of medical creeds, medical truths and medical fictions. Old Physic has for several centuries past drifted in the wrong direction, striking occasionally upon a rock, but finds itself to day further off from shore than ever before. Medicine, the oldest and most important of all branches of science, has not kept up with developments in other departments, but the rays of light have already deeply penetrated into the darkness of the past, fast undermining the building of the so-called "Rational Medicine" with all its hypothesis and traditions. * * * * * It was near the end of the last century, that the idea occurred to a single man, that the reason he had failed in practice must be that the medical profession was entirely on the wrong path. He made the effort to cure diseases on the principle directly opposite to those on which he had been educated to act, and he was successful. He thought a reformation of medicine needful and desirable, and proper to be attempted. He set about it, hoping, if he should succeed in pointing out a more safe, certain and pleasant road to the life-giving and life-renewing fountain of health, that it would be a blessing to suffering humanity. That man was SAMUEL HAHNEMANN. Had the reform inaugurated by him been of an insignificant character, it might have been accepted by the medical world without controversy. Had the new path into which he invited the profession been only a little smoother than the old one and lying right alongside of it, like that which led the pilgrims from the main high-way into the domains of the giant, physicians might have been easily lured into it. But the revolution was a radical one. It contemplated a counter-march such as the teachers and practitoners of the healing art had never been called upon to make. It called upon the chiefs of the profession to reverse the wheels of the ponderous engine, and seek for the long-sought shore in the opposite direction. The new doctrine came forth embodied in only three simple words: "_Similia Similibus Curantur_."