Heredity of the Memory. 47 



miracle is neither conceived by reason nor justified by experience. 

 We may, indeed, state such a proposition verbally ; but so soon as 

 we pass from words to things, from vagueness to precision, from 

 the imaginary to the real, we cannot form an idea of any such 

 annihilation in external or internal experience. 



Nor are the considerations in favour of the indestructibility of 

 our perceptions and ideas merely of a theoretical nature ; there 

 are also facts which, however strange they may appear at first, 

 are very simple, if we bear in mind that in the mental world, as 

 elsewhere, nothing perishes. Works on medicine and psychology 

 cite numerous instances where languages apparently altogether 

 forgotten, or memories apparently effaced, are suddenly brought 

 back to consciousness by a nervous disorder, by fever, opium, 

 hasheesh, or simply by intoxication. Coleridge tells a story of a 

 servant-maid, who, in a fever, spoke Greek, Hebrew, and Latin ; 

 Erasmus mentions an Italian who spoke German, though he had 

 forgotten that language for twenty years ; there is also a case 

 recorded of a butcher's boy who, when insane, recited passages 

 from the Phedre which he had heard only once. All these facts 

 are so well known that they need only here be cited ; they, with 

 many others, prove that in the depths of the soul there exists many 

 a memory which seemed to have vanished for ever. 



The physiological study of perception further shows that the pro- 

 duction of the phenomena of consciousness is subject to the law 

 of the transformation of force. Though this point is yet beset 

 with difficulties, the works of Mateucci and of Dubois-Reymond 

 show that electric currents are produced in the nerves, and are 

 there in continual circulation. When sensation takes place, and in 

 general whenever a nerve is active, there is produced a diminution 

 of its special current, as is indicated by the needle of a galvano- 

 meter connected with the nerve. This diminution takes place 

 because a molecular change is produced within the nerve, which, 

 on reaching the muscles, produces a contraction, and on reaching 

 the brain produces a sensation ; in other words, sensation is work, 

 and to perform work a certain force has to be expended and trans- 

 formed. The electrical forces which serve to produce the sensation 

 could not, at the same time, either give motion to a magnetic 

 needle or produce chemical decomposition, because, while per 



