DISEASE OF THE BODY A MENTAL STIMULANT. 75 



" flowed easily and felicitously, without any difficulty to lay hold of 

 them or to find appropriate language" (which, by the way, is more 

 than all would say who had read Scott's " Life of Bonaparte," and cer- 

 tainly more than can be said of his secretar}*, unless it really was a 

 familiar experience with him to be unable to lay hold of his thoughts). 

 " This was evident by the absence of all solicitude (miseria cogitandi) 

 from his countenance. He sat in his chair, from which he rose now 

 and then, took a volume from the bookcase, consulted it, and restored it 

 to the shelf all without intermission in the current of ideas, which con- 

 tinued to be delivered with no less readiness than if his mind had been 

 wholly occupied with the words he was uttering. It soon became ap- 

 parent to me, however, that he was carrying on two distinct trains of 

 thought, one of which was already arranged and in the act of being 

 spoken, while at the same time he was in advance, considering what 

 was afterward to be said. This I discovered " (he should rather have 

 said, "this I was led to infer") "by his sometimes introducing a word 

 which was wdiolly out of place entertained instead of denied, for ex- 

 ample but which I presently found to belong to the next sentence, 

 perhaps four or five lines further on, which he had been preparing at 

 the very moment when he gave me the words of the one that preceded 

 it." In the same way the present writer has unconsciously substituted 

 one word for another in lecturing, the word used always belonging to 

 a later sentence than the word intended to be used. We have noticed 

 also this peculiarity, that, when a substitution of this kind has been 

 once made, an effort is required to avoid repeating the mistake, even if 

 it be not repeated quite unconsciously to the end of the discourse. In 

 this way, for example, the writer once throughout an entire lecture 

 used the word "heavens" for the word "screen" (the screen on which 

 lantern pictures were shown). A similar peculiarity may be noticed 

 with written errors. Thus in a treatise on a scientific subject, in which 

 the utmost care had been given to minute points of detail, the present 

 writer once wrote " seconds " for " minutes " throughout several pages 

 in fact, from the place where first the error was made, to the end of 

 the chapter. (See the first edition of Proctor's " Transits of Venus," 

 pp. 131-136, noting as an additional peculiarity that the whole object 

 of the chapter, in which this mistake was made, was to show how many 

 minutes of difference existed between the occurrence of certain events.) 

 An even more curious instance of a mistake arising from doing one 

 thing while thinking of another occurred to the writer fourteen years 

 ago. He was correcting the proof-sheets of an astronomical treatise in 

 which occurred these words : " Calling the mean distance of the earth 

 1, Saturn's mean distance is 9*539 ; again, calling the earth's period 1, 

 Saturn's mean period is 29*457 : now, what relation exists between 

 these numbers 9*539 and 29*457 and their powers ? The first is less 

 than the second, but the square of the first is plainly greater than the 

 second ; we must therefore try higher powers," etc. The passage was 



