70 SIR WILLIAM HAMILTON'S PHILOSOPHY. 



science. The ordinary opinions of men will always oppose obstacles 

 enough to the progress of scientific thought ; and it is unfortunate that 

 Sir W. Hamilton should even have made an appearance of countenan- 

 cing that kind of opposition to the advancement of the science, in whose 

 service few lives have been so faithfully spent. Still it is due to hira 

 to remember that the mistake be has made is in diametrical opposition 

 to general principles of investigation which he has himself prescribed. 



Reviewing our discussion of the belief or conviction revealed in the 

 perception of external things, we see that it is but one of the pheno- 

 mena of the human mind which it is the office of mental science to 

 study, and that therefore we should abandon science in favour of ordi- 

 nary unscientific opinion, were we to foreclose at- once all inquiry into 

 the origin and composition of this' belief by merely pleading that in the 

 consciousness of all men it appears as a simple and ultimate fact. We 

 bave now, therefore, the way cleared for this inquiry, and for an esami- 

 nation of Sir "W. Hamilton's contributions to its settlement. 



(B). In proceeding then to consider whether any scientific explana- 

 tion can be given of perception, except by regarding it as one of the 

 elements of which human consciousness is built up, it is necessary to 

 eliminate from the phenomenon all that is non-essential. Now, it will 

 certainly be admitted by all that, in order to an act of perception, there 

 must be something perceived, and perceived as something difi^erent 

 from the perceiver. This is the highest generalization under which the 

 objects of knowledge can be ranged; for in all knowledge there must 

 be a knower and that which is known. But the object of external 

 perception is, moreover, always perceived as liere or there, as extend- 

 ing from this point to that in various directions, as, it may be, moving 

 from this position to that; in other words, it is always perceived as 

 existing in space. I do not deny that it may be proved on scientific 

 grounds legitimate to use the word perception for acts of knowledge, in 

 which the object is known not under the relations of space; as, for 

 example, to speak of perceiving the smell or the taste of an apple, the 

 heat of a fire or the sting of a bee ; but it will be allowed by all who 

 understand the question we are now encountering, that it is advisable, 

 till this question is settled, to apply the term in a stricter sense, only to 

 those knowledges of which the object is perceived as occupying space. 

 The objects of perception must also be perceived as existing in time, 

 but this is a condition to which the objects of all consciousness are re- 

 stricted. Still further, the objects of perception are perceived as offer- 



