THE IMMORTALITY OF THE SOUL. 203 



protoplasmic body ; and in the unicellular protists it 

 is a part of their protoplasmic cell-body. In this 

 way we are brought once more to the psychic organs, 

 and to an appreciation of the fact that these material 

 organs are indispensable for the action of the soul ; 

 but the soul itself is actual — it is the sum-total of 

 their physiological functions. 



However, the idea of a specific " soul-substance " 

 found in the dualistic philosophers who admit such a 

 thing is very different from this. They conceive the 

 immortal soul to be material, yet invisible, and 

 essentially different from the visible body which it 

 inhabits. Thus invisibility comes to be regarded as a 

 most important attribute of the soul. Some, in fact, 

 compare the soul with ether, and regard it, like ether, 

 as an extremely subtle, light, and highly elastic 

 material, an imponderable agency, that fills the 

 intervals between the ponderable particles of the 

 living organism. Others compare the soul with the 

 wind and so give it a gaseous nature ; and it is this 

 simile which first found favour with primitive peoples, 

 and led in time to the familiar dualistic conception. 

 When a man died, the body remained as a lifeless 

 corpse, but the immortal soul " flew out of it with the 

 last breath." 



The comparison of the human soul with physical 

 ether as a qualitatively similar idea has assumed a 

 more concrete shape in recent times through the 

 great progress of optics and electricity (especially in 

 the last decade) ; for these sciences have taught us a 

 good deal about the energy of ether, and enabled us 

 to formulate certain conclusions as to the material 

 character of this all-pervading agency. As I intend 

 to describe these important discoveries later on (in 



