MENTAL OPERATIONS IX RELATION TO TIME. 105 



m-ission of nervous power come in evidence here, as 

 also the curious facts deduced from delicate astro- 

 nomical observations, showing that different observers 

 perceive and record phenomena under appreciable 

 average differences of time. 1 We go but little beyond 

 their material evidence in asserting that one mind is 

 more rapid than another in the pure operations of 

 thought, whether governed by the will or not. Common 

 observation here gives cogent proof, not solely of 

 differences in the minds of others, but of diversities, 

 well worthy of note, occurring at different times in our 

 own. Who is not conscious to himself of moments 

 when thoughts stream through the mind with more 

 than wonted force and rapidity ? when, to use Locke's 

 words, ' the mind will press forwards, and there is no 

 holding it in ? ' Who, on the other hand, is not con- 

 scious of times when the faculties are sluggish, when 

 reason halts as if unable to pursue a train of thought, 

 and the mind passes into vacant reverie, or is domi- 

 nated over by some single idea from which it cannot 

 disengage itself? Even the simple act of reading be- 

 comes an experiment of the differences of time in the 

 reception of ideas in different persons. Some, as a sort 

 of necessity, read or utter each word singly ; others 

 compass the meaning of many words by a glance. 

 Some explanation may be given of their diversities 



1 My friend Professor Mitchell, of the Cincinnati and Albany Obser- 

 vatories, published a formula of personal equation, founded on the relative 

 aptitudes of different observers as expressed by time. On this subject I 

 would advert to a curious passage in Lucretius (ii. 262 et seq.), where he 

 adverts to time as intervening between the act of the will, and the 

 sequent effect on the bodily organs. 



