130 CIRCULATION OF THE BLOOD. 



highest interest to the medical practitioner, how speedily is 

 pain relieved or removed by the detraction of blood, the appli- 

 cation of cupping-glasses, or the compression of the artery 

 which leads to a part? It sometimes vanishes as if by magic. 

 But these are topics that I must refer to my ' Medical Observa- 

 tions/ where they will be found exposed at length and explained. 



Some weak and inexperienced persons vainly seek by dia- 

 lectics and far-fetched arguments, either to upset or establish 

 things that are only to be founded on anatomical demonstration, 

 and believed on the evidence of the senses. He who truly de- 

 sires to be informed of the question in hand, and whether the 

 facts alleged be sensible, visible, or not, must be held bound 

 either to look for himself, or to take on trust the conclusions 

 to which they have come who have looked; and indeed there 

 is no higher method of attaining to assurance and certainty. 

 Who would pretend to persuade those who had never tasted 

 wine that it was a drink much pleasanter to the palate than 

 water? By what reasoning should we give the blind from birth 

 to know that the sun was luminous, and far surpassed the stars 

 in brightness? And so it is with the circulation of the blood, 

 which the world has now had before it for so many years, illus- 

 trated by proofs cognizable by the senses, and confirmed by 

 various experiments. No one has yet been found to dispute 

 the sensible facts, the motion, efflux and afflux of the blood, by 

 like observations based on the evidence of sense, or to oppose 

 the experiments adduced, by other experiments of the same 

 character; nay, no one has yet attempted an opposition on the 

 ground of ocular testimony. 



There have not been wanting many who, inexperienced and 

 ignorant of anatomy, and making no appeal to the senses in their 

 opposition, have, on the contrary, met it with empty assertions, 

 and mere suppositions, with assertions derived from the lessons of 

 teachers and captious cavillings; many, too, have vainly sought 

 refuge in words, and these not always very nicely chosen, but 

 reproachful and contumelious; which, however, have no farther 

 effect than to expose their utterer's vanity and weakness, and ill 

 breeding and lack of the arguments that are to be sought in the 

 conclusions of the senses, and false sophistical reasonings that 

 seem utterly opposed to sense. Even as the waves of the 

 Sicilian sea, excited by the blast, dash against the rocks around 



