QUALITIES OF SENSATIONS. 465 



skin with a given sensation, and whenever afterwards the 

 nerve-fibres coming from the finger are stimulated, no mat- 

 ter where, we ascribe the origin of the sensation to some- 

 thing acting on the finger-tip. 



The Differences between Sensations. In both groups 

 of sensations, those derived through organs of special 

 sense and those due to organs of common, sensation, we dis- 

 tinguish kinds which are absolutely dislinct foT* our con- 

 sciousness, and not comparable mentally. We can never 

 get confused between a sight, a sound, and a touch, nor be- 

 tween pain, hunger, and nausea; nor can we compare them 

 with one another; each is sui generis. The fundamental 

 difference which thus separates one sensation from another 

 is its modality. Sensations of the same modality may differ; 

 but they shadeT imperceptibly into one another, and are com- 

 parable between themselves in two ways. First, as regards 

 quality; while a high and a low pitched note are both 

 auditory sensations, they are nevertheless different and yet 

 intelligibly comparable; and so are blue and red objects. 

 In the second place, sensations of the same modality are 

 distinguishable and comparable as to amount or intensity: 

 we readily recognize and compare a loud and a weak sound 

 of the same pitch; a bright and feeble light of the same 

 color; an acute and a slight pain of the same general char- 

 acter. Our^jsej^tdpj^ aspects of 



^modality, quality within the same modality, and intensity. 

 Certain sensations also differ in what is known as the 

 '[local sign" a difference by which we tell a touch on one 

 part of the skin from a similar touch on another; or an ob- 

 ject exciting one part of the eye from an object like it, but 

 in a different location in space and exciting another part of 

 the visual surface. 



As regards modality, we commonly distinguish five 

 senses, those of sight, sound, touch, taste, and smell; to 

 these, temperature must be added. The varieties of 

 common sensation are also several; for example, pain, 

 hunger, satiety, thirst, nausea, malaise, lien etre (feel- 

 ing " good"), fatigue. The muscular sense stands on the 

 intermediate line between specIaTand common sensations; 



