382 SIR WILLIAM HAMILTON S PHILOSOPHY. 



the kaovviedge coaveyed through the eye that such observation si 

 Ihnited. But what sense is constructed to receive impressions from 

 the phenomena of mind? through what function of the eye can one 

 see a thought or a wish ? In putting this question it is not denied 

 that there is a special portion of the brain or a special action of its 

 fibres on which self-consciousness depends ; and that, therefore, self- 

 consciousness may have in the nervous system an organ which, by 

 analogy with the organs of other mental acts, might be named a sense. 

 While, hovicver, the existence of such an organ is still a mere hypo- 

 thesis suggested by the general correlations of mental and nervous 

 actions, it is not by such an organ that observations are made upon 

 the brain : and even it such an organ were discovered, the discovery 

 could aOord no assistance towards ascertaining the peculiar nature of 

 those phenomena of which it is the organ. On the other hand, these 

 phenomena, — the actions which I perform, the states in which I 

 exist, — never occur without that knowledge of them which is com- 

 monly named consciousness ; and without this knowledge it would be as 

 impossible to conceive their peculiar nature as it is for the congenitally 

 blind to Ibrm any conception of colour. 



It is, therefore, evident that, without entrenching on the peculiar 

 ground of physiology, the psychological method of studying mental 

 science may be easily vindicated in opposition to an intolerant organ- 

 ology ; but it still remains a question, what place in that science is to 

 be assigned to the science which investigates the organ of mind ? The 

 doctrine of Sir William Hamilton, as we have seen, in its opposition 

 to phrenology, goes to the extreme of maintaining, "that no assistance 

 is afforded to Mental Philsophy by an examination of the Nervous 

 System." There is, however, an a priori improbability in such a 

 doctrine. The general connection of the sciences, which every year is 

 rendering more extensive and more intimate, makes Hamilton's asser- 

 tion, in its absoluteness, untenable ; but it is specially unhkely that 

 two sciences, so closely related as the philosophy of the mind and the 

 physiology of the nervous system, should be of no assistance to one 

 another ; and it would not be difficult to show that there must be 

 between them a mutual and beneficial reaction. It is altogether im- 

 possible, for example, to analyse so complex a phenomenon as any one 

 act of sense-perception into its constituent elements so as to extricate 

 the purely mental without ascertainining the nervous processes by 

 which they have been conditioned ; and the determination of many 



