OF THE BRITISH ASSOCIATION. 229 



confess that what we call disturbing causes are simply those parts of the true 

 circumstances which we do not know or have neglected, and we endeavour in 

 future to take account of them. We thus acknowledge that the so-called dis- 

 turbance is a mere figment of the mind, not a fact of nature, and that in 

 natural action there is no disturbance. 



But this is not the only way in which the harmony of the material with 

 the mental operation may be disturbed. The mind of the mathematician is 

 subject to many disturbing causes, such as fatigue, loss of memory, and hasty 

 conclusions ; and it is found that, from these and other causes, mathematicians 

 make mistakes. 



I am not prepared to deny that, to some mind of a higher order than 

 ours, each of these errors might be traced to the regular operation of the laws 

 of actual thinking ; in fact we ourselves often do detect, not only errors of 

 calculation, but the causes of these errors. This, however, by no means alters 

 our conviction that they are errors, and that one process of thought is right 

 and another process wrong. 



One of the most profound mathematicians and thinkers of our time, the 

 late George Boole, when reflecting on the precise and almost mathematical 

 character of the laws of right thinking as compared with the exceedingly per- 

 plexing though perhaps equally determinate laws of actual and fallible thinking, 

 was led to another of those points of view from which Science seems to look 

 out into a region beyond her own domain. . 



"We must admit," he says, "that there exist laws" (of thought) "which 

 even the rigour of their mathematical forms does not preserve from violation. 

 We must ascribe to them an authority, the essence of which does not consist 

 in power, a supremacy which the analogy of the inviolable order of the natural 

 world in no way assists us to comprehend." 



