35 



instead of being distinct and different, are really so inti- 

 mately correlated, and interdependent that the higher may 

 be regarded as simply a development of the lower, and 

 that while " there is no mode of mental activity which may 

 not be produced under its unconscious form," for every 

 conscious form' there is a corresponding unconscious one. 

 " The phenomena which constitute physical and mental life, 

 taken in their totality, seem to form a continuous series of 

 such a nature that at the one extremity of the series all is 

 unconscious and purely physiological, and at the other end 

 all is conscious and purely psychological ; and that the 

 transition from the one extreme to the other is performed 

 by insensible gradations, whether it be that the unconscious 

 rises to the conscious, or that the conscious returns to 

 unconsciousness. The purely physiological phenomena 

 appear to be reduced in the last analysis to motion^ and 

 purely psychological phenomena to sensation.' 1 



From what I have thus far stated it will be seen that the 

 development of the mind depends entirely upon the 

 development of the brain, and that psychological heredity 

 has its source -and antecedent in physiological heredity. 

 That this is so will appear all the more evident when we 

 consider that all that we have and are, as individuals con- 

 stituted for the performance of certain functions, we owe 

 to heredity, with the exception of the developing influences 

 of our " environment " through life, and the educational 

 processes to which we have been subjected. For if mental 

 development is ever, and in all cases, subject to organic 

 conditions, as it undoubtedly is ; and if, with the organism, 

 the nervous diathesis and structure of the parents are 

 inherited their mental capacities and peculiarities must 

 1 Ribot. 



