Education 165 



accepts them, not because of the biologic proofs, 

 but because they coincide with the accepted 

 view. What are "ids" and "determinants" 

 but new names for the old apartments in which 

 the mind is assumed to be divided ? And the 

 more one has of them, the greater is his power 

 to struggle and to survive. We must there- 

 fore increase the number of apartments, the 

 weight or the size of the brain, or the num- 

 ber of ids and determinants. All this is the 

 same thought expressed in different words, in 

 whatever form it reflects the popular thought. 

 It may be called progress by addition, for it 

 assumes that additional matter makes for supe- 

 riority and determines contests in survival. 



I do not intend to argue against this theory, 

 or to establish another one. We need not so 

 much proof of a new theory as a clear pres- 

 entation of the basis on which one may rest. 

 Men adopt a theory to explain facts, but the 

 old one survives, in spite of inherent difficul- 

 ties, until the new is so clearly formulated as 

 to displace it. I wish, therefore, to contrast 

 a theory of progress by differentiation with a 

 theory of progress by addition, and to show 



