The scepticism which already at that period had begun to take possession of many of the best minds manifested itself in the form of a disbelief in the possibility of discovering full scientific truth, and men therefore taught the doctrine that the human understanding is not capable of attaining anything higher than probability. The acceptance of such a doctrine naturally acted as a powerful hindrance to all further original research. And so the Empirics neglected the study of anatomy and physiology as something quite superfluous and unprofitable. They gave no further thought to the causes of disease, and were quite satisfied simply to observe its manifestations, to investigate the factors which appeared to bring it into a state of activity, and to search for the means of effecting a cure. In carrying on work of this character, they of course derived help, not only from their own experience, but also from that of others--which latter became in time a matter of history. When they encountered new experiences and were unable to supply a satisfactory explanation they resorted to a third method--that of reasoning by analogy. Upon this triple support--one’s own individual experience, the experience of others stored up in the form of history, and reasoning by analogy--rested the entire structure of empiricism. Strange as it may at first appear, the science of medicine from this time onward made no further conspicuous progress until the middle of the seventeenth century of the present era. In certain branches of practical medicine--as, for example, pharmacology, obstetrics and general surgery, and also in certain special departments--the Empirics made a number of material additions to our knowledge; but in all essential particulars the medical science taught throughout this period of about two thousand years varied but little from that taught at Alexandria one hundred or two hundred years before the birth of Christ. This extraordinary phenomenon of almost complete arrest of development for so long a period of time should not excite surprise, for something of a similar nature has certainly occurred in other departments of human knowledge.