32 G PROGRESS OF SCIENCE IN THE CENTURY. 



postulate of " vital force." This postulate is a 

 vague one and its content has altered greatly even 

 during the nineteenth century. For a time " vital 

 force " was spoken of as a " hyper-mechanical " 

 factor, a mystical power, a non-material agent, pre- 

 siding over the activities of the body. But reason 

 could not " repose on this pillow of obscure quali- 

 ties," and the content of the postulate changed, for 

 it is difficult to believe that Johannes Miiller meant 

 more by his vitalism than to express the fact that 

 the physical and chemical processes in the living 

 body are correlated in a manner which defies re- 

 statement in simpler terms. Many nowadays would 

 agree with this or would advance to the more posi- 

 tive idealist position occupied by Bunge. This 

 physiologist declares that " it would indeed be a lack 

 of intelligence to expect with the senses to make 

 discoveries in living nature of a different order to 

 those revealed to us in inorganic nature," and yet he 

 maintains " that all the processes of our organism 

 capable of explanation on mechanical principles are 

 as little to be regarded as vital phenomena as the 

 rustling of leaves on a tree, or as the movement of 

 the pollen when blown from stamen to pistil." In 

 other words, he holds that the distinctively vital does 

 not admit of mechanical restatement, and that light 

 must come from above, not from below, i.e., from 

 psychological rather than physical concepts. 



Many other opinions of authoritative experts 

 might be cited, varying greatly in their form, but 

 with this common basis of agreement that the phe- 

 nomena of life cannot be restated in the language of 

 chemistry and physics. And yet, the reader may 

 well ask, " Is this more than a pious opinion, an argu- 

 mentum ad ignorantiam? Is not biological anal- 



