22O Heredity. 



ii. 



The psychological study of unconscious phenomena dates from 

 scarcely half a century back, and is yet in its first stages. The 

 school of Descartes and that of Locke that is to say, the whole 

 seventeenth and eighteenth centuries expressly held that psych- 

 ology has the same limits as consciousness, and ends with it. What 

 lies without consciousness is remanded to physiology, and between 

 the two sciences the line of demarcation is absolute. Consequently, 

 all those penumbral phenomena which form the transition from 

 clear consciousness to perfect unconsciousness were forgotten, and 

 not without injurious consequences, for hence came superficial 

 explanations, and insufficient and incomplete views. The nature 

 of things cannot be violated with impunity ; and as everything in 

 nature forms series, continuity, insensible transitions, our sharp 

 divisions are always false. If we did not lose sight of the fact that 

 our subdivisions of universal science into particular sciences, how- 

 ever useful and even indispensable, are always artificial and arbi- 

 trary on one side or another, we should be saved much idle dis- 

 cussion. Thus, as regards the unconscious phenomena which 

 pertain at once to physiology and psychology, it makes very little 

 difference which of these two sciences is occupied with them, 

 provided only that they be studied, and studied well. 



Leibnitz alone in the seventeenth century saw the importance of 

 this. Less was not to be expected of the inventor of the infini- 

 tesimal calculus, the apologist of the Lex continui in natura^ the 

 man who in the highest degree possessed the faculty of insight. 

 By his distinction between perception (conscious) and apperception 

 (unconscious), he opened up a road on which in our times most 

 physiologists and psychologists have somewhat tardily entered. 

 There is, however, as yet no comprehensive work on this question, 1 

 and the undertaking would be no light one; for a psychology of 



1 The completest and most recent work on this subject is Hartmann's 

 Philosophy of the Unconscious (Philosophic des Unbewussten, Versuch einer Welt- 

 anschauung, Berlin, 1869). The author takes a metaphysical point of view 

 close to that of Schelling and Schopenhauer ; but he gives a good number of 

 facts, some of which will be hereafter quoted. 



