CHAPTER II. 



The Causation of Gross Material Effects— The Causation of Atomic and 

 Molecular Effects. 



Let ns now briefly apply the conclusions arrived at in the last 

 chapter — first, to gross material effects; and secondly, to the 

 more minute atomic and molecular effects. Under this latter 

 head are included the chemical changes of protoplasm, the 

 sum of which constitutes life. Having thus acquired a scientific 

 insight into the causation of atomic and molecular pheno- 

 mena, and consequently of the vital changes of protoplasm, 

 we shall (I believe) be in a position to define the cause of 

 disease in intelligible terms, disease being an abnormal mode 

 of life. 



First, as regards gross material effects : let us, in theory, 

 construct a planetary system containing a given number of 

 worlds, each having a definite mass and velocity, and all bear- 

 ing definite relations to one another. In such a case, we are 

 ourselves the choosers of the material conditions, and we can, 

 from two well-known laws, calculate the resulting complex 

 series of movements with the utmost accuracy, the two being : 

 the law of universal gravitation and the first law of motion. 

 These laws are simply verbal expressions of sequences which 

 are the outcome of the ultimate properties of matter already 

 spoken of. What then is the cause, in this hypothetical case, 

 of the complex series of movements ? It is the sum of the 

 material conditions. Let any one of them be altered — e.g., 

 the mass of any one world— and the entire series of move- 

 ments will be changed. It is very important to note that 

 all the material conditions which take part in the produc- 

 tion of a given effect constitute the cause, and not any one 

 of them. 



To make this point clear, let us conceive a nicely constructed 



