106 



exposition of the theory in which ail such mathematical 

 development shoiild be altogether banished. 



The présent paper is the outcome of this résolve. It 

 covers the lecture given before the scientifîc section, but 

 has been slightly extended and completed by the addition 

 of the necessary tables, which will make the reader com- 

 pletely independent of the more extended technical papers. 

 Meanwhile a popular account like the présent does not, 

 of course, prétend to supersede the more technical papers 

 altogether. Leaving aside most of what seems to hâve 

 more of a theoretical than of a practical importance (for 

 the former I hâve still to refer the reader to our second 

 paper) it tries to give a clear insight in the essentiel points 

 of the method and to work thèse out with sufiîcient détail 

 for practical application. 



Before concluding the introduction I wish to repeat the 

 words of the introduction to the 2nd paper: 



"The main purpose of both papers — the finding 

 something about causes — is no doubt an ambitious one. 

 Indeed it may be well to warn expressly against too 

 sanguine expectations. The theory necessarily starts from 

 certain assumptions. Thèse assumptions are probably not 

 or not fuUy realized in nature. Therefore it is impossible 

 to say a priori in how far our theory will apply to the 

 cases ofîered by nature. The main ground for not being 

 altogether sceptical lies in the fact that a close approach 

 to the normal curve has already been found to occur 

 frequently. Now our theory is only as it were an 

 extension of the mathematical theory which leads to the 

 normal curve and this extension starts from what is 

 certainly in innumerable cases a "uera causa" viz that the 

 "déviations" are dépendent on the size already reached 

 by the individuels. A reasoning like that of art. 9 of the 

 first paper (art. 11 of the présent one), shows this with 

 perfect évidence. 



