Of it may be truly said that none of its principles are conclusively demonstrated, and that every alleged fact relating to it must be received only as a variable and fluctuating approach to truth; and if such is the case for those who have been, as far as may be, perfected in the science and art of medicine, much more emphatically is it so of the undergraduate. For him it is eminently true that "the aim of university teaching is not to perfect the student in knowledge, but to prepare him to learn." It is not absolute truth which men in general are competent to understand, nor is anyone competent to teach them; neither are they able duly to estimate those partial and approximate truths which even philosophers discern but dimly. Out of the multitude of devotees a few only are qualified to approach the sacred shrine. Even the most learned and gifted hardly do more than see it through a glass darkly. To the mass of mankind a faint and distant vision is alone possible. And even for them symbols of truth are provided in the formulæ of philosophy, and in the creeds and ceremonials of religion, which crudely overlie essential verities which even the acutest minds can but faintly behold and imperfectly comprehend.
In the remarks that are to follow I shall endeavor to illustrate the uncertainty of therapeutical laws, and show that it depends neither upon themselves, nor solely upon the fallibility of human judgment, but chiefly upon the extreme complexity and obscurity of the problems that occur in practical medicine. In that department of knowledge there is no constant quantity whatever, neither the physician, nor the patient, nor the remedy. The very complexity and uncertainty of clinical problems render the practice of medicine at once the most difficult and one of the most interesting of arts; interesting because its very purpose is the alleviation of suffering and the saving of life; difficult because its problems are the most complex the mind can examine; and uncertain because it concerns laws which, even as they relate to physical phenomena are very imperfectly known, while the relations of the mind to the body which it so powerfully affects can hardly be said to be known at all.
There was a period, and it lasted for centuries while the Galenical theories dominated the medical world, when the word of the Master drowned the voice of Nature. The falsely called science of mediæval times, which was too often as baseless as the clouds and as unstable as the sands of the desert, filled the schools with barren disputes and chimerical notions of the nature of diseases and their cures, and too
