On the Mechanical Conception of Nature. 641 



she need not therefore always finish off, and 

 indeed can never close her account, since she will 

 never be in a position to solve all problems. 3 But 

 science must not for this reason pronounce any 

 question to be insoluble simply because it has not 

 yet been completely solved ; this she does, how- 

 ever, as soon as she renounces the possibility of 

 a mechanical explanation by invoking the aid of a 

 metaphysical principle. 



That this is the correct mode of scientific 

 investigation is seen by the abandoning of the 

 (ontogenetic) vital force. The latter is no longer 

 admitted by anybody, now that we have turned 

 from mere speculation to the investigation of 

 Nature's processes ; nevertheless its non-existence 

 has not been demonstrated, nor are we yet in a 

 position to prove that all the phenomena of life 

 must be traced to purely physico-chemical pro- 

 cesses, to say nothing of our being actually able 

 to thus trace them. Von Baer also states " that 

 the abolishment of the vital force is an important 

 advance ; it is the reduction of the phenomena of 

 life to physico-chemical processes, although these 



* This obviously does not imply that the naturalist should 

 not investigate Nature's processes, and not only correlate these, 

 but also work them up into a universal conception ; this is 

 indeed both desirable and necessary if natural knowledge is 

 to be regarded in its true value. The naturalist by this means 

 becomes a philosopher, and the vitality of the so-called 

 " natural philosopher " has been inspired, not by the necessity 

 for investigation, but by philosophy proper. 



