68 A METHOD OF MEASURING THE DEVELOPMENT 



hand will arrange the weights more successfully. Another 

 reason is that all of our tests presuppose an effort of attention 

 and the attention varies during a period of concentration, 

 especially with young people ; now it is intense ; one minute 

 later it is relaxed. Suppose that the subject has a moment 

 of distraction, of embarrassment, of ennui during a test, it 

 may cause complete failure. One cannot doubt the justice 

 of this last reason. We are so convinced on this point that 

 we think it chimerical and absurd to judge the intelligence 

 of a child by one test alone. 



The preceding considerations lead to the conclusion that 

 the intellectual level of a child can be judged only by a group 

 of tests. It is success in several distinct tests which alone is 

 characteristic. Intelligence cannot be estimated as can the 

 height. For height it suffices to have a table of mean heights for 

 the various ages ; given a child we measure it, and then turn to 

 the table of means ; it is very easy by a simple comparison to 

 ascertain whether the child measures up to the standard height of 

 children of his age, or whether he is retarded one year, two years, 

 etc., or, on the contrary is advanced one year, two years, etc. 

 There is very little artificiality about this method of estimation. 



It is altogether otherwise when we estimate the intelli- 

 gence. If one wishes to apply the same system of comparison 

 between the intelligence of one child and the mean intelli- 

 gence of children of different ages one is arrested by the 

 difficulty which we have mentioned above ; a child is retarded 

 for certain tests of his age and advanced for others. We think, 

 however, that this difficulty can be overcome ; but it is on 

 condition that we adopt some convention ; and the said con- 

 vention, be it the best possible, will always give to the pro- 

 ceeding an artificial character. If by chance another conven- 

 tion had been adopted sensibly dififerent results would have 

 been reached. We feel it necessary to insist on this fact, be- 

 cause later, for the sake of simplicity of statement, we will 

 speak of a child of eight years having the intelligence of a 

 child of seven or of nine years; these expressions if accepted 

 arbitrarily may give place to illusions. It is necessary to re- 



