VI PREFACE. 



with another, but to the comparison afforded by different 

 points of examination in the use of the same faculty, so that 

 we may reasonably assume, where such verification is un- 

 fairly excluded, that we are entitled to suspend our judgment 

 in all cases in which immediate decision is not absolutely 

 necessary. But it is a singular fact in connection with 

 this subject that almost all animals are made with dupli- 

 cates of each of their faculties, as if to supply by com- 

 parison a check to the inaccuracy of the faculty within 

 itself. Thus we have duplicate brains as well as dupli- 

 cate eyes ; and while a man with two eyes sees with both, 

 and would detect imperfection in one eye by means of the 

 accuracy of the other, so we have reason to believe that a 

 man thinks in duplicate, or with both lobes of the brain, 

 although from the co-operation of the organs only one 

 single train of thought is apparent ; just as by the use of 

 both eyes one subject is alone presented in consequence 

 of the co-operation of both organs of vision : for it has 

 been found that where one of the lobes of the brain has 

 been so injured as to be incapable of action, a perfectly 

 sane and healthy power of mind has been maintained in 

 the individual by the sound action of the other lobe of the 

 brain only, just as accurate vision may be experienced by 

 a person having only one eye, or shutting the other. The 

 explanation of this power is not referrible to the physical, 

 but to the metaphysical part of our being, as will be better 

 understood by what we have introduced on the subject of 

 Consciousness ; for there is just as much a duplicate of 

 thought produced in employing both lobes of the brain as 

 there are two physical images when both eyes are used 

 the unity experienced in each case existing in the com- 

 bining power of the Consciousness only. 



J. A. S. 

 Sept. 1868. 



