1901.] on Memory. 603 



parts are within the elastic limits of the tissue, and of these no 

 memory remains ; while other parts are distorted to various extents, 

 aud of these the endurance of the memory is in proportion to the 

 degree of the distortion. In every distortion of tissue there are two 

 elements to be considered : viz. the area over which it is distributed, 

 aud the degrees of change within that area; the number of particles 

 displaced, and the amount of their displacement — and the amount of 

 displacement differs much in different parts of the area. 



The distortion of a body under the incidence of motion may be 

 within or without the limit of elasticity of the body. If it is within 

 the limit of elasticity, no set, no structural memory remains ; and 

 thus it is that of a vast number of our experiences we retain no 

 memory at all. The faces that meet us in the street, the stones and 

 cart tracks in the road, the leaves on the trees, the scraps of con- 

 versation, nay, much in the books we read, and in discourses that we 

 hear, it may be in church, it may be in some scientific assembly such 

 as this, are gone the instant they cease to impress the senses, and 

 leave not a trace behind. And when the limit of elasticity is ex- 

 ceeded, and a temporary set remains, we have to recognise that it may 

 vary much within the limits of the disturbed area. We have to regard 

 the change both in its extension and in its intension ; both in regard 

 to the area over which it is distributed, and to the degrees of change 

 within that area ; both with regard to the number of particles dis- 

 placed, and to the degree of their displacement. It may well happen, 

 and in point of fact it does always happen, that the amount of dis- 

 tortion suffered by the area affected differs much in different parts of 

 that area. Some parts are not displaced except within the elastic 

 limit, and of the corresponding parts of the experience no structural 

 memory remains — no conscious memory is possible. Of the parts 

 that receive a set, the degree of set is not the same in all, and con- 

 sequently the endurance of the memory differs much as to different 

 parts of the experience. 



Suppose that you arrive overnight in a foreign town, and when 

 you look out of your window in the morning you see a varied land- 

 scape of mountain and lake, tower and town, foliage and snow. You 

 turn away from the window, and instantly the greater portion of the 

 scene is gone. No memory at all is retained of a thousand details 

 which undoubtedly did impress the retina, and which, by appropriate 

 means, might have been made to produce memories. Whatever dis- 

 tortion of tissue was produced by the motion arriving from these 

 objects was within the elastic limit of the tissue, and the instant the 

 distorting agent ceased to act, the distortion disappeared. There- 

 after you do not find that the memories that you have acquired of the 

 scene fade uniformly. What you retain, as years elapse, is not a 

 fading uniform memory of the whole, but rather that it goes bit by 

 bit. One part after another fades out until all that is left are the 

 most striking features, — on the left-front a mountain of vague shape, 

 from which all detail and all colour, save a white top, has gone ; on 



