402 



SCIENCE 



[N. S. Vol. XLII. No. 1082 



term "energy" to the two quite distinct 

 conceptions involved in its subdivisions into 

 potential and kinetic energy. 



Enough has been said to show that the 

 peculiar powers necessary for the study of 

 one of the most abstract branches of knowl- 

 edge may be expressed in terms which 

 bring them down to the level at which com- 

 parison with other subjects is possible. Ap- 

 plying the same reasoning to other occupa- 

 tions, the same conclusion is inevitable. 

 The commercial man, the politician and the 

 artist must all possess the type of memory 

 best suited to concentrate in the field of 

 mental vision their own experiences as well 

 as what they have learned from the ex- 

 perience of others ; and, further, they must 

 have the power of selecting out of a multi- 

 tude of possible lines of action the one that 

 leads to success; it is this power which 

 Poincare calls the inventive faculty. 



The argument must not be pushed too 

 far, as it would be absurd to affirm that all 

 differences in the capability of dealing suc- 

 cessfully with the peculiar problems that 

 occur in the various professions may be 

 reduced to peculiarities of memory. I do 

 not even wish to assert that Poincare 's con- 

 clusions should be accepted without quali- 

 fication in the special case discussed by him. 

 What is essential, to my mind, is to treat 

 the question seriously, and to dismiss the 

 vague generalities which, by drawing an 

 artificial barrier between different groups 

 of professions, try to cure real or imagi- 

 nary defects through plausible though quite 

 illusory remedies. All these recommenda- 

 tions are based on the fallacy that special 

 gifts are associated with different occupa- 

 tions. Sometimes we are recommended to 

 hand over the affairs of the nation to men 

 of business ; sometimes we are told that sal- 

 vation can only be found in scientific meth- 

 ods — what is a man of business, and what 

 is a scientific method 1 If you define a man 



of business to be one capable of managing 

 large and complicated transactions, the in- 

 ference becomes self-evident; but if it be 

 asserted that only the specialized training 

 in commercial transactions can develop the 

 requisite faculties, the only proof of the 

 claim that could be valid would be the one 

 that would show that the great majority of 

 successful statesmen, or political leaders, 

 owed their success to their commercial ex- 

 perience. On the other hand, every method 

 that leads to a correct result must be called 

 a scientific method, and what requires sub- 

 stantiating is that scientific training is bet- 

 ter than other training for discovering the 

 correct method. This proof, as well as the 

 other, has not been, and, I think, can not be, 

 given. When, therefore, one man calls for 

 the conduct of affairs "on business lines" 

 and the other clamors for scientific meth- 

 ods, they either want the same thing or they 

 talk nonsense. The weak point of these 

 assertions contrasting different classes of 

 human efforts is that each class selects its 

 own strongest men for comparison with the 

 weakest on the other side. 



The most fatal distinction that can be 

 made is the one which brings men of 

 theory into opposition to men of practise, 

 without regard to the obvious truth that 

 nothing of value is ever done which does 

 not involve both theory and practise ; while 

 theory is sometimes overbearing and irri- 

 tating, there are among those who jeer at it 

 some 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 dog- 

 matic of dogmatics who tirades against 

 dogma, and only the most hopeless of theo- 

 rists can declare that a thing may be right 

 in theory and wrong in practise. 



Why does a theory ever fail, though it 



