1893.] on The Just- Perceptible Difference. 17 



Sir Percivale concludes just as Wordsworth's admirers formerly 

 had done : " I knew not all he meant." 



Now, in the Nineteenth Century of the present month Mr. Knowles, 

 in his article entitled " Aspects of Tennyson," mentions a conversa- 

 tional incident curiously parallel to Wordsworth's own remarks 

 about himself : — " He [Tennyson] said to me one day, * Sometimes as 

 I sit alone in this great room I get carried away, out of sense and 

 body, and rapt into mere existence, till the accidental touch or 

 movement of one of my own fingers is like a great shock and blow, 

 and brings the body back with a terrible start.' " 



Considering how often the imagination is sufficiently intense to 

 mimic a real sensation, a vastly greater number of cases must 

 exist in which it excites the physiological centres in too feeble a 

 degree for their response to reach to the level of consciousness. So 

 that if the imagination has been anyhow set into motion, it shall, as 

 a rule, originate what may be termed incomplete sensations, and 

 whenever one of these concurs with a real sensation of the same kind, 

 it would swell its volume. 



This supposition admits of being submitted to experiment by 

 comparing the amount of stimulus required to produce a just-per- 

 ceptible sensation, under the two conditions of the imagination being 

 either excited or passive. 



Several conditions have to be observed in designing suitable 

 experiments. The imagined sensation and the real sensation must be 

 of the same quality ; an expected scream and an actual groan could 

 not reinforce one another. Again, the place where the ima^e is 

 localised in the theatre of the imagination must be the same as it is 

 in the real sensation. This condition requires to be more carefully 

 regarded in respect to the visual imagination than to that of th© 

 other senses, because the theatre of the visual imagination is described 

 by most persons, though not by all, as internal, whereas the theatre 

 of actual vision is external. The important part played by points of 

 reference in visual illusions is to be explained by the aid they afford 

 in compelling the imaginary figures to externalise themselves, super- 

 imposing them on fragments of a reality. Then the visualisation 

 and the actual vision fuse together in some parts, and supplement 

 each other elsewhere. 



The theatre of audition is by no means so purely external as that 

 of sight. Certain persuasive tones of voice sink deeply, as it were, 

 into the mind, and even simulate our own original sentiments. The 

 power of localising external sounds, which is almost absent in those 

 who are deaf with one ear, is very imperfect generally, otherwise the 

 illusions of the ventriloquist would be impossible. There was an 

 account in the newspapers a few weeks ago of an Austrian lady of 

 rank who purchased a parrot at a high price, as being able to repeat 

 the Paternoster in seven different languages. She took the bird 

 home, but it was mute. At last it was discovered that the apparent 

 performances of the parrot had been due to the ventriloquism of the 



Vol. XTV (No. 87.) o 



