"The Law of Substance" 15 



must be considered illegitimate as a weapon 

 wherewith to attack other systems, so far as 

 they too are equally entitled to be considered 

 reasonable guesses at truth. 



The central scientific doctrines upon 

 which Professor Haeckers philosophy is 

 founded appear to be two one physical, 

 the other biological. The physical doctrine 

 is what he calls " the Law of Substance " a 

 kind of combination of the conservation of 

 matter and the conservation of energy : a 

 law to which he attaches extraordinary 

 importance, and from which he draws 

 momentous conclusions. Ultimately he 

 seems to regard this law as almost axiomatic, 

 in the sense that a philosopher who has 

 properly grasped it is unable to conceive the 

 negative. A few extracts will suffice to 

 show the remarkable importance which he 

 attaches to this law : 



"All the particular advances of physics and 

 chemistry yield in theoretical importance to the 

 discovery of the great law which brings them to 

 one common focus, the c law of substance.' As 



