10 PRESIDENT S ADDRESS. 



men of theory into opposition to men of practice, without regard to the 

 obvious truth that nothing of value is ever done whicli does not involve 

 both theory and practice. While theory is sometimes overbearing and 

 irritating, there are among those who jeer at it, at any rate, a few to 

 whom Disraeli's definition applies: the practical man is the man who 

 practises the errors of his forefathers. With refined cruelty Nemesis 

 infects us with the disease most nearly akin to that which it pleases 

 us to detect in others. It is the most dogmatic of dogmatics who tirades 

 against dogma, and only the most hopeless of theorists can declare that 

 a thing may be right in theory and wrong in practice. 



Why does a theory ever fail, though it may be sound in reasoning? 

 It can only do so because every problem involves a much larger number 

 of conditions than those which the investigator can take into account. 

 He therefore rejects those which he believes to be unessential, and if 

 his judgment is at fault he goes wrong. But the practical man will 

 often fail for the same reason. When not supported by theoretical 

 knowledge he generalizes the result of an observation or experiment, 

 applying it to cases where the result is determined by an altogether 

 different set of conditions. To be infallible the theorist would have 

 to take account of an infinite number of circumstances, and his calcula- 

 tions would become unmanageable, while the experimenter would have 

 to perform an infinite number of experiments, and both would only 

 be able to draw correct conclusions after an infinite lapse of time. 

 They have to trust their intuition in selecting what can be omitted with 

 impunity, and, if they fail, it is mainly due to the same defect of 

 judgment. And so it is in all professions: failure results from the 

 omission of essential considerations which change the venue of the 

 problem. 



Though theory and practice can only come into opposition when one 

 of them is at fault, there is undoubtedly a contrast of character and 

 temperament between those who incline more towards the one and 

 those who prefer the other aspect: some like a solitary life at the 

 desk, while others enjoy being brought into contact with their fellows. 

 There have at all times been men predestined by nature to be leaders, 

 and leadership is required in all branches of knowledge — the theoretical 

 as well as the more active pursuits; but we must distrust a man's 

 own estimate of his power to convert his thoughts into acts. In 

 the ordinary affairs of life a man who calls himself a man of action 

 is frequently only one who cannot give any reasons for his actions. 

 To claim that title justly a man must act deliberately, have confidence 

 in his own judgment, sufficient tenacity of purpose to carry it through, 

 and sufficient courage to run the unavoidable risks of possible failure. 

 These risks may be trivial or they may be all-important. They mav 



