SEVENTEENTH AND EIGHTEENTH CENTURIES l8l 

 mentally different from mechanism, that consequently the mechanical 

 physiology which his contemporaries universally accepted must be utterly 

 repudiated. In the living organism the soul is the essential part; the body 

 exists for the sake of the soul and is controlled by the soul. As a proof of 

 this assertion he quotes, to start with, a number of ancient Aristotelean 

 arguments on the finality of the structure of the body. Further, he declares 

 that the existence of the body is due to a thing which is in itself foreign to the 

 essence of the body, but, on the other hand, is akin to the essence of the soul, 

 owing to its immateriality — namely, motion. The soul's function consists 

 in going from object to object and comparing them, and the maintenance 

 of the body by means of mental activity and constant moving goes on, sub- 

 ject to the will of the soul, as the result of motions suited to the objects that 

 the soul requires. The fact that Stahl thus calls motion "thing" and com- 

 pares it with the soul in contrast to the body proves that at any rate he had 

 learnt nothing from Galileo and Newton. If, then, we find in this and other 

 similar arguments the utter hollowness of Stahl's philosophical speculations, 

 he has on other occasions an exceptionally keen eye, trained through his 

 chemical studies for the essential in the composition of organism. As some- 

 thing essential to all the constituents of the body he points out the extreme 

 easiness and rapidity with which they are chemically decomposed. This 

 property evidently made a great impression on him; he constantly reverts 

 to it and searches for an explanation for it, but it is obvious that, with the 

 fundamental ideas that he once embraced, it is always the soul which ulti- 

 mately keeps the body together and prevents it from disintegrating. This 

 easy deccmposability is considered to be due to a very complicated chemical 

 combination in its constituent parts — a fact that differentiates it from 

 ordinary chemical associations. The chemical quality is different in different 

 forms of life and peculiar to each individual. Finally, the constituent parts 

 of the body possess, besides their chemical quality, a special "texture" and 

 "structure": the former an arrangement of the smallest parts of the body, 

 the latter a combination of the elements thus formed, these two factors being 

 characteristic for every living being. "Living body is nothing else than that 

 which has structure," he declares. It is hardly necessary to lay special stress 

 on the fact that as a result of all this investigation into the chemical nature 

 of organism Stahl advanced science a long way; both the complex composi- 

 tion and the resultant easy decomposability of the constituent parts of the 

 living body are indeed facts of fundamental importance for modern biology, 

 and of still greater importance is his postulate that structure is something 

 peculiar to the living organism in contrast to dead natural objects. Here 

 Stahl has without doubt had some presentiment as to the significance of 

 tissue structure as a basis of life in all its forms; that he was unable to follow 

 up the idea to a conclusion of immense value to science was certainly due 



