WHAT IS PHYSICAL LIFE 



edge, however, dispelled all that, until it 

 changed thunder itself from an awe-in- 

 spiring voice into only a loud noise. 



But it was in accounting for the phe- 

 nomena of life in Nature that this old con- 

 ception lasted the longest. A sort of 

 supernatural, vital force was imagined to 

 be the only explanation here, and in med- 

 ical science particularly this imaginary 

 vital force arrested all progress for many 

 centuries. 



But this once crudely conceived myth- 

 ical vital force remains as a name to dis- 

 turb the reasoning of those who repudiate 

 its existence. Because there is no vital 

 force, therefore it is concluded that what 

 things and forces we know of must ac- 

 count for life by supplying everything 

 needed both for its origin and for its 

 developments. Those things are, first, 

 matter as a substance, and then such 

 forces we know of that act on matter, 



