§ 4. =Ancient Medicine and Magic.=—But how is it possible that the ancient physicians, and even the most enlightened minds among them, should not only have tolerated such a crass medical superstition as the above examples have shown us, but should even have incorporated them in their works? Incomprehensible, however, as this fact may appear to the modern practitioner, it becomes conceivable if the condition of antique medicine and of the medical profession of ancient times is considered. In the first place, ancient medical science adopted an entirely different mode of diagnostico-theoretical method than that employed by professors of medicine in modern times. Ancient natural science (compare also Chapter V. of this work), as well as ancient medicine, obtained their scientific views exclusively by deduction—_i.e._, they deduced individual results from general presumptions, or, rather, they construed, by reason of some general presumption, the physico-medical consequences which were to follow from such a general supposition. If this attempt to obtain an insight into physical processes is extremely hazardous, it becomes still more precarious when the manner and means in which these general presumptions were arrived at were primarily of an entirely hypothetical nature. It is true, no fundamental objection can be raised to this method, as even modern natural science and medicine, despite the fact that their methods of investigation in a diagnostico-theoretical respect scarcely admit of material objections, can not do without hypothesis. But hypothesis is not always mere hypothesis. It is well known that there are hypotheses which, even in the minds of the most conscientious investigators, are not inferior to that knowledge which is obtained by experiment and observation, whereas other hypotheses again present the distinct stamp of insufficiency and makeshift. The trustworthiness and the heuristic value of an hypothesis depend upon the quality of the diagnostico-theoretical process by means of which it was obtained. If this process has been such as physical investigation is bound to insist upon, the hypothesis thus arrived at is fully justified to supply the still absent data with regard to the phenomena in question. This, however, can be accomplished by hypothesis only when the latter is not set forth until it plainly appears that, in spite of a conscientious and orderly arrangement of observation after observation, of experiment upon experiment, without the admission of logical loopholes, full data in regard to the nature of the phenomena is not forthcoming. In such a case we may consider as actually proven by hypothesis what observation and systematic experiment, continuous and logical, were intended to prove, and failed. However, this inductive hypothesis is alone entitled to be considered in medicine. Naturally, such an inductive hypothesis was not thought of by the ancients, as the inductive method of investigation