The utter futility of the speculative method as a means of attaining effective knowledge is completely demonstrated by the stagnation and inefficiency of medicine under its influence for thousands of years. The only sure and effective way of gaining knowledge is the empirical method, by patient observation and investigation, the tardy adoption of which was the sole means by which internal medicine has been revolutionized and vivified. The keynote of the true method was struck by John Hunter in his advice to Jenner when the latter was beginning to ponder on the subject of vaccination, "Do not think; investigate." The whole history of medicine is an imposing demonstration of the futility of theorizing and the utility of scientific investigation. This lesson should come home to every one of us, and indicate the only mental attitude we can safely assume. We should formulate our judgments only by the objective and empirical route. We should avoid dogmatism, premature theorizing, and generalization from insufficient data. We should frankly admit our ignorance, and not deceive ourselves or others by unfounded assumptions. We should practise a healthy skepticism, and carefully scrutinize the information offered us. No authority is too eminent, no traditions too ancient, to be exempt from criticism. The vast amounts of chaff in our professional literature need to be carefully sifted for the few kernels of truth; while to a far greater extent the ready acceptance of the interested representations of commercial establishments is a mark of naive simplicity and easy credulity. Always as the test of verity should be demanded the evidence of and agreement with an ample body of objective data. These considerations may seem trite, yet experience constantly demonstrates the necessity for their vigilant observance.
It is disquieting to reflect on the inefficiency and even harmfulness of much of the medical practise of the past. Yet our predecessors were men of sincerity and high ideals, and had the trust and confidence of the mass of the people. The therapeutic successes of the past must be construed mainly as an exemplification of the potency and action of psychotherapy.
Although the scientific method imposes rigorous criteria for the acceptance of doctrines, yet truths so established rest on a firm and abiding basis. For this reason we can feel confidence in the validity and permanency of such of our present medical theory and practise as has a thorough scientific basis. We have good reason to feel that at last we have attained some degree of finality in many of our doctrines; that the medicine of to-day is radically different from the ephemeral systems of the past and wherever thoroughly grounded on a scientific foundation will stand for all time.
If it be true that medicine has only just emerged from the middle ages, some medieval error must still persist in our doctrines and