Ixx THE LIFE OF HARVEY. 



derings in the labyrinth of the metaphysics of physiological 

 science, he did enough to deter .any one from attempting to 

 tread such barren ground again. In his work on the Heart 

 and Blood, Harvey had all the essential facts of the subject 

 clearly before him, and he used them at once in such masterly- 

 wise, that he left little or nothing for addition either by himself 

 or others. Secure of his footing here, he could well dispense 

 with " vital spirits/' " innate heat," and other inscrutable agen- 

 cies, he could leave " adequate and efficient causes/' and other 

 metaphysical phantoms on one side it was physics that he 

 1 was dealing with, and the physician was at home. With the 

 information we now possess, we see clearly how indifferently 

 weaponed was the physiologist of the year 1647 for encountering 

 such a subject as Animal Generation ; a Leeuwenhoek and a 

 De Graaf, a Spallanzani and a Haighton, a Wolff, a Purkinje, 

 a Von Baer, a Valentin, a Rudolph Wagner, a Bischoff, and 

 many more, had successively to appear, before the facts of the 

 subject could be ascertained, and a Schleiden and a Schwann 

 were further necessary as ultimate interpreters of the things 

 observed before they could be either rightly or wholly under- 

 stood. No wonder then that The Physiologist of the 17th cen- 

 tury, meets us in the guise of one rather puzzled with the bur- 

 then he has made up his mind to bear, and, contrary to his former 

 wont, eking out the lack of positive knowledge by reiterated 

 disquisitions on topics where certainty is unattainable. 



It is rather curious, moreover, to find Harvey, in his work 

 on Generation, not entirely escaping the pitfall of which he 

 was so well aware, and which he shunned so successfully in 

 his earlier production. In the work on the Heart, he sets out 

 with the certainty that the whole of the notions of the 

 ancients on the heart and blood are untenable ; and then, 

 taking Nature for his guide, his fine intellect never once suffers 

 him to stray from the right path. In the book on Generation, 

 on the other hand, he begins by putting himself in some sort 



