CLASSIFICATION OF KNOWLEDGE 11 



psychology. Moreover, a number of complex sciences 

 involve combinations of physics, biology, and psycho- 

 logy in different proportions, and are represented 

 by points within the triangle, where the colours are 

 mixtures of the primaries. 



Let us begin a more detailed survey somewhere 

 in the purple region, at the beginnings of physical 

 science. Here we find the so-called laws of thought, 

 logic both verbal and symbolic, the latter contain- 

 ing the fundamental principles of mathematics. A 

 little further on are the developments of pure mathe- 

 matics leading to, and elsewhere lying side by side 

 with, the methods of applied mathematics ready for 

 use in physical problems. Then comes mechanics, 

 experimental in its principles, but largely formed in 

 detail by mathematical deduction from those prin- 

 ciples. The next region of our figure, the red corner, 

 contains, more or less side by side, the various 

 branches of physics proper : heat, light, sound, 

 electricity and magnetism. Here, too, we may 

 place chemistry, which in its essence is probably 

 only a branch of molecular physics, though it may 

 extend further along the length of the side of the 

 triangle, and run more into the biological region 

 than do some other subjects comprised in physics. 



Next we pass into the yellow region the physics 

 and chemistry of vital processes, one aspect of 

 physiology, animal and vegetable. With the other 

 aspect, that concerned first with the cell and then 



