102 MENTAL OPERATIONS IN RELATION TO TIME. 



phenomena a limited interpretation, it is true, since 

 we really know nothing of that mysterious mechanism 

 by which one thought engenders another, or the 

 memories of past things are revived, sometimes after 

 half a life has gone by without a shadow of them having 

 crossed us. All that has been written upon the asso- 

 ciation of ideas and memory, with or without the aid 

 of cerebral anatomy, is but a confession of this igno- 

 rance. The work of Hartley, which I can recollect as 

 still in some repute, was a futile attempt to explain 

 phenomena mechanically, which the better science of 

 our own time has shown to be inapplicable. 



Eeceding from what is impossible, let us see what 

 may really be gained by this manner of regarding the 

 mental states as a series successive in time. And first, 

 as to the amount of power the mind has, or habitually 

 exercises, in determining these successions. Such power 

 is evidently a limited and fluctuating one. Thoughts 

 and emotions are ever coming in upon us unbidden or 

 despite the will ; clinging to us as moments of mental 

 existence with more or less tenacity, displaced either 

 by mental effort or by external causes. All this is true 

 as regards the action and changes of the mind within 

 itself, apart from things without. I am speaking here 

 of what are really familiar facts, but not duly noted as 

 such, or followed to the conclusions they suggest. 



Foremost among such conclusions is that of the 

 great difference of different minds, as regards the 

 power of governing these sequences of state of initia- 

 ting a series, and holding to it steadily, despite hin- 

 drances from without and changing or suspending the 



