46 ON SOME ASPECTS OF THE 



silence, but generally he fails to do so ; he becomes 

 greatly perturbed, and denies everything, even the most 

 demonstrable facts. There is no greater incentive to 

 unreasonable anger than the conviction that our position 

 has been shown to be erroneous, and that in our inmost 

 souls we are fully conscious of its hopeless character. 



Thus it was with many of the critics of the work of 

 the scientific method ; a scientific inference was first 

 branded as a dangerous perversion of traditional truth ; 

 then it was lampooned as a ridiculous absurdity ; then 

 it was admitted to be plausible, but, after all, open to 

 grave doubt. And, finally, should all doubt vanish, what 

 course was left but to indicate politely that the reasoner 

 was himself untrustworthy and the description of the 

 phenomena which he adduced a tissue of falsehoods ? 



From many striking instances of this sort of hostility 

 I select one in my own province of science, the opposition 

 to the demonstration by the illustrious Harvey of the 

 circulation of the blood. The details of this demonstra- 

 tion were set forth in 1628 in the celebrated disquisition 

 upon the motion of the heart and blood in animals. In 

 this Harvey ' marches victorious from position to position 

 until the whole truth is clearly put before the reader'. 1 

 The stages in this demonstration are briefly these : the 

 construction and action of the heart which must receive 

 blood only by the veins and pump it out into the 

 arteries ; the direction of the actual blood flow in the 

 arteries ever from those parts nearer the heart towards 

 those parts farther off; the construction of the veins 

 containing valves which permitted the blood to flow in 

 one direction only, that being towards the heart. Since 

 the flow of blood continues without cessation during the 

 whole of life only one conclusion is logically admissible : 

 1 See M. Foster, The History of Physiology. 



