PHYSICAL CAUSATION. 



advancing to a second position until the first one has been 

 firmly established. He does not permit himself to indulge 

 in crude fancies, but reasons only concerning the results of 

 rigid and exact experiment. But no sooner does he leave 

 his own special department and enter upon the considera- 

 tion of the forces of organic nature, than he abandons the 

 principles of investigation he has himself laid down, allows 

 his fancy to revel in the wildest theories, and puts forward 

 as rigid facts what are really but vague assumptions. He 

 sports in metaphor, and dallies with allegory, while at the 

 same time he is vehement about " the inexorable logic of 

 facts." Nay, some of the disciples of the new philosophy, 

 not content with slow advance, have spoken very strongly 

 and have dared to invoke the forces of coercive dogma. They 

 have promulgated a new faith, the first article of which is, 

 that the only forces in nature have been derived from the 

 sun. " Then," say they, as " vital axe natural forces it follows 

 that vital force is solar energy, and that the sun is the source 

 of all life." This dogma being accepted it is easy to 

 convince the trusting proselyte that in the production of 

 higher and more elaborate structures a greater amount of 

 solar energy must be absorbed and rendered latent than in 

 the foimation of very simple living organisms, and that the 

 comparatively simple vegetable structure differs from the 

 higher and more complex animal form in the number of 

 force units which have been elaborated and modified. In 

 the formation of a complex cell with high endowments, a 

 much greater amount of energy is required and rendered 

 latent than in the production of a simple cell ; and it follows 

 as a corollary that by the death and destruction of one of 

 the brain cells of man, for example, a much greater amount 



