Literary Notices. xxi 



but to the relations of concepts to percepts, and of percepts to other per- 

 cepts. It swee|5s tlirough the whole gamut of mental development. It 

 is a law of the assimilation or incorporation of like with like. Progress is 

 effected by the elimination of the incongruous. 



Assimilation presupposes an environment of that which is capable of 

 assimilation. And the environment in which mind develops is a mental 

 environment. That is a fact too often lost sight of. Consciousness never 

 comes in contact with aught but other facts of consciousness. The mental 

 symbolism is one and continuous and self-contained. There is no getting 

 outside it. If mind does grow up in correspondence with something that 

 is not mind this is a matter of metaphysical psychogenesis, not of positive 

 psychogenesis with which alone I am now concerned. From the positive 

 point of view mind develops in conformity with a mental environment 

 and with that alone — an environment of percepts directly suggested from 

 without and of concepts growing out of perceptual experience or suggested 

 through inter-communication with our fellow-men. And the environment 

 is not unchanging, but is itself subject to development. Each thinker not 

 only has his thoughts moulded by the intellectual environment but reacts 

 upon it, making it for the future something different from what it was. 

 The thinker in any department of knowledge brings his mind into contact 

 with all that is best in human thought and endeavour in that department. 

 He thus finds his true environment and endeavours to make it more con- 

 gruous by further elimination of incongruities. That I feel sure is how 

 science has advanced. First the congruous system is allowed to take 

 form in the individual thinker's mind by the assimilation of all that is best 

 in the work of his precursors ; by the rigorous application of scientific 

 method and verification some of the remaining incongruities are elimina- 

 ted; and then through the thinker's influence the nmended and e.\tended 

 system is impressed on the science and philosophy of his time and of all 

 after time. The environment is henceforward no longer the same. This 

 I could amply illustrate; but not here and now. 



The environment is henceforward no longer the same. This constant 

 change — for the better as we hope— of the envij-onment of the developing 

 mind makes it exceedingly difficult, if not impossible, to test the truth of 

 the theory of use-inheritance, already adverted to, in the matter of the 

 mental faculties of man. ... It will of course be observed that in 

 contending that the law of psychogenesis is a law of development by the 

 elimination of the incongruous, I am not pretending to account for the 



