43 



stuff. It is my part to-day to show that before 

 motionless stuff before the problem of the "pri- 

 mum mobile" even Harvey himself stood help- 

 less ; helpless yet fascinated by the indulgence of 

 invention when, in the De motu cordis, or the 

 De generatione, he permitted himself to carry 

 contemplation beyond the sphere of his admirable 

 experiments. "Natural, vital and animal spirits" 

 indeed he would have none of ; saying well that he 

 should want as many spirits as functions, and that 

 to introduce such agents as artificers of tissues is 

 to go beyond experience : yet in his need of a 

 motor for his machine he was not able to divest 

 himself of the language nor even of the philosophy 

 of his day ; he referred the cause of the motion of 

 the blood, and therefore of the heart, to innate 

 heat 1 . In his day he could not but regard rest and 



1 Held by Gilbert, and attributed to Averroes ; but older 

 than Averroes. In turning to Francis Bacon's hypothesis I read 

 (Ed. E. and S. ii. 263. Hist. Densi et rari chapter/' Dilatationes 

 per spiritum innatum se expandentem," a Paracelsian sort of 

 chapter) " Pulsus cordis et arteriarum in animalibus fit per 

 irrequietam dilatationem spirituum, et receptum ipsoruin, per 

 vices." The muscular quality of the heart was known to 

 Galen, forgotten, and rediscovered, Spiritus vitalis, for Bacon, 

 was "aura composita ex flamma et aere" (cf. ^En. vi. 747). 

 Glisson has been fortunate in two generous judges, in Haller 



