1901.] on Memory. 605 



proved ; but it cannot be improved by charms, or nostrums, or 

 conjuring tricks. There is but one way to improve the memory, and 

 that is by patient and persistent labour. The only help that science 

 can give is to show how that labour can be least wastefully employed. 

 It has been insisted, I fear with wearisome iteration, that structural 

 memory, with which we are now dealing, is not peculiar to the brain 

 tissue, nor even to living matter. It is common to all solids ; and in 

 all solids, under practically all circumstances, it is found that the 

 inertia of the particles is diminished, and the production of set 

 facilitated, by increasing the quantity of free motion among the 

 particles. If we want to forge a bar of iron into a new shape, we 

 can immensely facilitate the production of the set that we wish to 

 impose by heating the bar to redness ; that is to say, by greatly in- 

 creasing the individual motion of its particles. The maker of whips 

 or walking-sticks who wishes to bend a hook on a stick, or to straighten 

 a kink out of its shaft, puts the stick in a bath of hot sand, and when 

 he has by this means increased sufficiently the intrinsic motion of its 

 particles, he can bend the stick into what shape he will, and whatever 

 shape he then gives it will endure. The set is easily imposed, and it 

 is permanent. And in the brain tissue also the production of set is 

 facilitated by increase in the intrinsic motion of the particles of the 

 tissue, for we find that whenever the brain is unusually active, the 

 events that are then experienced are remembered with unusual 

 tenacity. We find, for example, that the impressions that we ex- 

 perience in times of great emotional storm and stress are remembered 

 with extraordinary faithfulness for very long periods. Of all that I 

 experienced in the year 1866 I remember vividly the events of one 

 night only, and that the night in which I was shipwrecked ; but of 

 that night I have still a very vivid remembrance. Dr. Johnson 

 retained to the end of his life a memory of the appearance of Queen 

 Anne, who touched him for the Evil when he was under three years 

 old, and we can imagine how highly excited the child must have been 

 at such a tremendous experience, and can understand therefore why he 

 remembered it so well. Any one who has been in peril of his life in 

 a burning house remembers for the rest of his life incidents that the 

 firemen who rescue him have forgotten in five minutes, for the im- 

 pression is made in the one case on a brain already in a state of high 

 activity, in the other on brains which are comparatively quiescent. 

 In these considerations, however, we gain but little practical aid, for 

 a system of mnemonics which could ensure our recollecting an event 

 only by burning down a house when it happened would be too costly 

 for everyday use. Fortunately this is not our only expedient. 



There is another mental state in which we have reason to believe 

 that the intrinsic motion of the cerebral elements is increased, and in 

 this state also experiences produce memories that are peculiarly 

 enduring. This is the state that we call Attention. What may be 

 the precise cerebral condition that underlies the act of attention we 

 do not certainly know, but we can scarcely be wrong in asserting 



