286 BEVIEWS— SIB WM. HAMILTON'S 



doctrine of philosophers ; for some have thought that sensations, as 

 mental states, are capable of being distinguished from the act8 of 

 intelligence by which a knowledge of them is realised. In fact, it 

 has been held, and by no mean authorities, that sensations may 

 exist in the mind, without ever becoming known at all. But accord- 

 ing to Hamilton such opinions are untenable. He denies that sense, 

 either in its lower or in its higher form, can be discriminated from 

 intelligence. " Quid erit sensus," he asks with Tertullian, " nisi 

 ejus rei quae sentitur intellectus ?" 



Sensation is not only an act of knowledge, but more particularly, 

 one of immediate knowledge or consciousness. As we shall have 

 frequent occasion to use these expressions, immediate hnowledge f 

 and consciousness, it may be well to define them formally. An 

 object is said to be known immediately, when it is apprehended in 

 itself ; in contradistinction to mediate knowledge, which takes place 

 when an object is apprehended through something else. Thus, a 

 blind man, made sensible through means of his staff, of an obstacle 

 before him, knows the obstacle, but only through something else. 

 This is mediate knowledge. On the other hand, how is one aware of 

 the thought which at any moment exists in his mind ? He 

 apprehends it, not through anything else, but in itself. This is 

 immediate knowledge. Consciousness is employed by Sir "Wm. 

 Hamilton, and will be used throughout this article, as synonimous 

 with immediate knowledge. "When therefore sensation is represent- 

 ed as an act of immediate knowledge or consciousness, the meaning 

 is, that the object known in sensation is apprehended in itself, and 

 not through the medium of aught else. 



This leads to the enquiry, what is the object of which we are 

 conscious in sensation ? Sensation is an act of knowledge ; it is an 

 act of immediate knowledge : what is the thing immediately known ? 



In answer to this we remark that the living organism of the body 

 is capable of having a great variety of affections excited in it, either 

 by external or by intraorganic causes. In the well-known theory of 

 Dr. Eeid, such affections are recognised as the antecedents of our 

 sensations. The sensation of sweetness, for example, is consequent 

 upon one particular modification of the animated organism ; the 

 sensation of redness upon another ; the sensation of the odour of a 

 rose, upon a third ; and so forth. The sensorial affections which are 

 thus regarded by Eeid as the antecedents of our sensations, constitute, 

 according to Hamilton, the objects known in sensation. The living 

 organism, in consequence of the application of some stimulus, is 

 affected in a certain way ; the mind immediately knows, or becomes 



