128 Presidential Address 



sometimes be brought about. Mental and spiritual opera- 

 tions, such as prayer, realised as efficacious by religious 

 people, appear to be partially of this nature. 



Page 97 



The semi-jocular parable about "Poynting's Theorem" 

 here interjected will only be appreciated by physicists. It 

 is a mathematical theorem that when electric and magnetic 

 fields are superposed at right angles to each other a third 

 element is at once introduced, an element of progression 

 or advance of energy at right angles to both, and of value 

 equal to their vector product. It is in this way that light 

 advances, and that telegraphic messages, wireless and other, 

 are conveyed. Of the three elements, electricity, mag- 

 netism, and motion, when any two are supplied the third 

 necessarily supervenes. This is the basis of ordinary dy- 

 namos and of electric motors, as well as of many other more 

 recondite things. The Theorem with many illustrations 

 was published in the Philosophical Transactions of the 

 Royal Society for 1884. 



Page 98 



The human evil in the world can be regarded as the price 

 to be paid for human freedom. The highest product of 

 evolution is not a set of automata mechanically con- 

 strained or coerced to go right, but human beings, knowing 

 good and evil, who can go wrong if they choose, and whose 

 will to do right gradually develops; at a cost in suffering 

 and error, great indeed, but not too great for the worth- 

 whileness of the ultimate product. This point of view is 

 more fully explained in my book Man and the Universe 

 and other such writings. 



The outstanding difficulty always felt about reconciling 

 freedom with fixed law is dealt with in the first article of 



