SCIENTIFIC METHOD 47 



this blood always flowing from the heart into an arterial 

 system, and to the heart from a venous system, must 

 find its way across from the arteries to the veins and 

 thus circulate. Harvey s difficulty lay in the circumstance 

 that as the microscope was not in use, no known path 

 existed by which the blood could be conveyed from the 

 smallest arteries into the smallest veins; there was 

 a gap in the vascular series, but his demonstration made 

 it a logical certainty that a bridge across this gap was 

 in existence. The convincing nature of the argument 

 must, one would have thought, have made the circulation 

 of the blood a logical necessity to every thinking man ; 

 yet though Harvey lived to his eightieth year he hardly 

 witnessed his great discovery established before he died ; 

 and it has been said that he was the only one of his 

 contemporaries who lived to see it in some repute ; no 

 physician adopted it, and when it got into vogue they 

 then disputed whether he was the discoverer. 



Even men of great intellectual attainments such as 

 Sir William Temple refused to credit the demonstration, 

 ridiculed as absurd the doctrine of the circulation of the 

 blood, and, to avoid the cogency of the argument, denied 

 the demonstrable facts. Temple finally appealed from 

 reason to that last resort of the baffled antagonist, the 

 verdict of common sense, and on this quicksand based 

 his disbelief. 'Sense/ he says, 'can hardly allow it, 

 which must be satisfied as well as reason before mankind 

 will concur V 



The irony of Temple's appeal is shown by the circum- 

 stance that already, before he made it, Malpighi had 

 bridged the gap by means of the microscope and actually 

 seen the phenomenon which common sense would not 

 allow. In 1 66 1, writing to Borelli, Malpighi described 

 1 Disraeli's Miscellanies of Literature. 



