6 THE BEGINNINGS OF LIFE. 



and darkness which previously enshrouded all vital 

 phenomena, and few, we suppose, would deny that the 

 results of their labours had sent gleams of light into 

 corners previously unillumined. However much there 

 may be of the mysterious and occult still remaining, 

 some of the phenomena, at least, formerly looked upon 

 as essentially c vital ' and, therefore, well-nigh in- 

 explicable are now recognized as depending in great 

 part upon purely physical processes. But before stating 

 what are the modern conceptions of Life what 

 views are now possible it will be well to glance 

 briefly at the labours of those who have helped to build 

 up that doctrine of the Correlation of Forces,, or Con- 

 servation of Energy, whose influence has been so great 

 in upsetting the old metaphysical conceptions to which 

 we have referred. 



It is not to be expected that the doctrine of the 

 Conservation of Energy should have sprung fully formed 

 from the brain of any single man. The progress of 

 scientific thought and experiment had been gradually 

 tending in this direction during the closing years of 

 the last century, and the doctrine has since been built 

 up and perfected by the labours of many workers and 

 thinkers. The germs of it are, however, to be found, 

 stated with remarkable clearness, even more than two 

 centuries ago, in the writings of Lord Bacon, who says 

 in the twentieth Aphorism of his c Novum Organum:' 

 c When I say of motion that it is the genus of which 

 heat is a species, I would be understood to mean, not 



