106 MENTAL OPERATIONS IX RELATION TO TIME. 



through that view of the phenomena of sleep which I 

 have dwelt upon elsewhere, as the only just exponent 

 of this great function of our nature. But self -conscious- 

 ness is the only true interpreter of these changes of 

 mood and state, which are ever going on in the indi- 

 vidual mind, from causes objective or subjective, known 

 or unknown. 



I have already spoken of the difficulty of thus 

 turning the mind inwards upon its own acts and states. 

 A yet greater difficulty is that of self -experiment upon 

 the conditions to try, for instance, what can be done 

 by pure effort of will in determining the objects and 

 sequences of thought which, in their common course, 

 are so largely governed by automatic associations of 

 former images and memories. An act of recollection 

 may in some sort be called an exercise of the mind 

 upon itself. But I have sometimes in my own case 

 made more explicit trial of this kind, making time a 

 part and test of the experiment. Within a minute I 

 have been able to coerce the mind, so to speak, into 

 more than a dozen acts or states of thought, so in- 

 congruous that no natural association could possibly 

 bring them into succession. In illustration I note here 

 certain objects which, with a watch before me, I have just 

 succeeded in compressing, distinctly and successively, 

 within thirty seconds of time the pyramids of Ghizeh; 

 the Ornithorhynchus, Julius Caesar, the Ottawa Falls, 

 the rings of Saturn, the Apollo Belvedere. This is an 

 experiment I have often made on myself, and with the 

 same general result. It would be hard to name or 

 describe the operation of mind by which these successive 



