394 ON SENSATION, AND THE ORGANS OF THE SENSES. 



the other, but it may be directed to those made on particular spots of either. 

 This may be noticed, again, in the process by which we make ourselves ac- 

 quainted with a landscape or a picture ; if our attention be directed to the whole 

 field of vision at once, we see nothing distinctly ; and it is only by abstracting 

 ourselves from the contemplation of the greater part of it, and by directing 

 our attention to smaller portions in succession, that we can obtain a definite 

 conception of the details. The same is the case in regard to auditory impres- 

 sions ; and here the power of attention, in causing one sensation or series of 

 sensations to predominate over others which are really more intense, is often 

 most remarkably manifested. When we are listening to a piece of music 

 played by a large orchestra, for example, we may either attend to the combined 

 effect of all the instruments, or we may single out any one part in the har- 

 mony, and follow this through all its mazes; and a person with a practised ear 

 (as it is commonly but erroneously termed, it being not the ear but the mind 

 that is practised), can even distinguish the sound of the weakest instrument 

 in the whole band, and can follow its strain through the whole performance. 

 This attention to a single element can only be given, however, by withdrawing 

 the mind from the perception of the rest ; and a musician who thus listens, 

 will have very little idea of the rest of the harmonic parts, or of the general 

 effect. In fact, when the mind is thus directed, by a strong effort of the will, 

 into a particular channel, it may be almost considered as unconscious quoad 

 any other impressions. 



520. The effects of this principle are manifested in regard to the sensations 

 which originate within the system ; as well as in respect to those which are 

 excited by external impressions. Every one is aware how difficult it is to 

 keep the body perfectly quiescent,* especially when there is a particular mo- 

 tive for doing so, and when the attention is strongly directed to the object. 

 This is experienced even whilst a Photogenic likeness is being taken, when 

 the position is chosen by the individual, and a support is adapted to assist 

 him in retaining it; and it is still more strongly felt by the performers in the 

 Tableaux Vivans, who cannot keep up the effort for more than three or four 

 minutes. Now it is well known that, when the attention is strongly directed 

 to an entirely different object (when we are listening, for example, to an elo- 

 quent sermon, or an interesting lecture), the body may remain perfectly mo- 

 tionless for a much longer period ; the uneasy sensations, which would other- 

 wise have occasioned the individual to change his position, not being felt; but 

 no sooner is the discourse ended, than a simultaneous movement of the whole 

 audience takes place, everyone then becoming conscious of some discomfort, 

 which he seeks to relieve. This is the case, also, in regard to the respiratory 

 sensation ; in general it may be observed, that the usual reflex movements are 

 not enough for the perfect aeration of the blood, and that a more prolonged 

 inspiration prompted by an uneasy feeling, takes place at intervals ; but under 

 such circumstances as those just alluded to, this feeling is not experienced, until 

 the attention ceases to be engaged by a more powerful stimulus, and then it 

 manifests itself by the deep inspirations which accompany, in almost every 

 individual, the general movement of the body. 



521. It is curious that the constant direction of the attention to internal 

 sensations of a subjective kind, should sometimes occasion actual disorder of 

 the parts to which these sensations are referred ; and yet this seems the only 

 way of accounting for some of the phenomena of disease. Sometimes the 

 cause of the sensation may exist in the trunk of the nerve, in some part of its 

 course; whilst in other instances, it may be confined to the sensorium. Pain 



* Of course the movements of respiration niul winking are left out of the question. 



