168 Sylvius and his Pupils. [lect. 



used the word phlogiston. In the Specimen Beccherianum 

 which Sylvius appended to his edition of the Physica, and 

 in which he expounds Beccher's theoretical views, he says, 

 " Briefly, in the act of composition, as an instrument there 

 " intervenes and is most potent, fire, flaming, fervid, hot ; 

 " but in the very substance of the compound there intervenes, 

 "as an ingredient, as it is commonly called, as a material 

 " principle and as a constituent part of the whole compound 

 " the material and principle of fire, not fire itself. This I was 

 " the first to call phlogiston." He had used the phrase several 

 years before, as early as 1697 at least. 



The pendulum swung far in one direction when Sylvius 

 threw aside all van Helmont's subtleties and spiritualistic 

 conceptions, his ferments which acted with a power higher than 

 and different from that governing ordinary chemical changes, 

 his archsei of which the ferments were the instruments, and 

 his sensitive soul of which the archaei were the servants — 

 threw T aside I say all these and maintained that the events of 

 the living body were ordinary chemical events, and attempted 

 to explain digestion, respiration, and everything else by means 

 of an effervescence like that which he witnessed when vitriol 

 was thrown on iron filings or on long-exposed ashes. But the 

 pendulum swung back again in the old direction, with as great 

 if not greater impetus when Stahl put forward and brilliantly 

 maintained the view that all the chemical events of the living 

 body, even though they might superficially resemble, were at 

 the bottom wholly different from the chemical changes taking- 

 place in the laboratory, since in the living body all chemical 

 changes were directly governed by the sensitive soul, anima 

 sensitiva, which pervaded all parts and presided over all even^f^ 



Stahl's 'sensitive soul,' of which I shall have somewhat 

 more to say in a subsequent Lecture, was something very 

 different both from the sensitive soul of van Helmont and 

 the rational soul of Descartes. To the latter indeed it 

 was, in truth, in full antagonism. In Descartes' view, the 

 human body apart from the rational soul was a machine, 

 and the phenomena of man, apart from those which were the 

 direct expression of the activity of the rational soul, were the 



