HARVEY'S WORK 67 



have, in fact, seldom or never been used by working 

 scientists. For the truth is there is no one method of 

 science : there are as many methods as there are men of 

 science, though doubtless most of those working at any 

 particular science have much in common. The task of 

 the man of science is first to observe the appearances 

 which Nature presents, then to ascertain what lies behind 

 those appearances, and, lastly, to link together his con- 

 clusions and observations into general laws. How he 

 does this is not a matter of much concern, so long as he 

 does it. Nor need he, as a man of science, concern 

 himself with the question of what are the ultimate truths 

 behind all the appearances that Nature presents to us. 

 He has but to express general laws according to the know- 

 ledge of his day, knowing full well that a day will almost 

 certainly come when his general laws and the ideas on 

 which they are based will have to be modified or replaced. 

 What is a matter of concern, however, and what does 

 vitally affect the course of science is not how his ideas come 

 to him, but how he proves or verifies the statements that he 

 makes. The vague analogies, the loosely put suggestions, 

 the confused reasoning of a Servetus may have the same 

 source as the finely worked out conclusions of a Harvey. 

 The two men are poles asunder when it comes to verifica- 

 tion. Servetus is content with a statement, the other 

 passes cautiously from observation to inference, from 

 inference to verification in an orderly and stately sequence. 

 We may note, too, the careful way in which Harvey limits 

 his problem. He refuses to be drawn beyond his subject. 

 He will deal only with the knowledge that he has, knowing 

 full well that further work may throw new light on his in- 

 vestigations. He sets out to discover the mechanical explana- 

 tion of the movement of the heart, and he accomplishes 

 his task triumphantly. But he will not be led aside by 

 those ancient wills-o'-the- wisp, the discussion of the nature 



