410 IMPRESSIONS AND SENSATIONS EQUALIZED. 



things, when that explanation is actually intruding itself before us. And 

 so in this case ; it was long "before the truth gleamed in upon me, before 

 my reasoning powers shook off the delusive impressions" of my senses. 

 But it occurred at last ; for I said to myself, Is it more probable that 

 such a mystery is true, or that I have dreamed for the third time that 

 which I had already dreamed of twice before ? Have I really seen the 

 blasted tree and the sunning turtle ? Are a weary ride of fifty miles, 

 the noontide heat, the silence that could almost be felt, no provocatives 

 to a dream ? I have ridden under such circumstances many a mile, fast 

 asleep, and have awoke and known it; and so I resolved that if ever 

 circumstances carried me to those parts again, I would satisfy myself as 

 to the matter. 



"Accordingly, when, after a few years, an incident led me to travel 

 there, I revisited the well-remembered scene. There still was the stag- 

 nant pool, but the blasted pine-tree was gone ; and after I had pushed 

 my horse through the marshy thicket as far as I could force him, and 

 then dismounted, and pursued a close investigation on foot in every di- 

 rection round the spot, I was clearly convinced that no pine-tree had ever 

 grown there ; not a stump, nor any token of its remains, could be seen ; 

 and so now I have concluded that, at the glimpse of the water, with the 

 readiness of those who are falling asleep, I had adopted an external fact 

 into a dream ; that it had aroused the trains of thought which, in former 

 years, had occupied me ; and that, in fine, the mystery was all a delusion, 

 and that I had been frightened with less than a shadow. " 



The instructive story of this physician teaches us how readily, and yet 

 how impressively, the remains of old ideas may be recalled ; how they 

 may, as it were, be projected into the space beyond us, and take a posi- 

 tion among existing realities. That such images arise from a physical 

 impression, which has formerly been made in the registering ganglia, it 

 is impossible to doubt, and that for their emergence from their dormant 

 state it is necessary that there should be a dulling or blunting of con- 

 Equalization of temporaneous sensations, so that these latent relics may 

 old impressions present themselves with a relatively equal force. This 



and new sensa- ,. . . -, -, 



tions necessary equalization of the intensity of an old impression with a 

 for visions. present sensation may be brought about in two different 

 ways : 1st. By Diminishing the force of present sensations, as when we 

 Modes of ac- are in a reverie, or have fallen asleep, or by breathing vapors 

 that^quaii? unsuited for the support of respiration ; 2d. By increasing the 

 zation. activity of those parts of the brain in which the old impres- 

 sions are stored up. On each of these a few remarks may be made. 



Cerebral vision depends on an equalization in intensity between pres- 

 ent sensations and old impressions. So long as the former predominate 

 in power, the latter excite no attention or are wholly overlooked. This 



