PHYSIOLOGICAL PARADOXES. 



of vision, and the brain is conscious of seeing 

 one moon only. 



But the influence of the barley bree, on 

 those who have had so much that they are 

 willing to admit they have "just had plenty," 

 is to interfere with the co-ordination of the 

 muscles. It does not paralyse the muscles, but 

 prevents their contractions from being adjusted 

 with exactness or certainty. Thus the ob- 

 server in this state will sometimes set his 

 eyes so that their lines of vision converge at 

 the distance B, the point B being the centre 

 of both fields of vision. Then the right eye 

 sees its image of the moon with one horn far 

 to the right of the field and the other a little 

 to the left, while the left eye sees one horn far 

 to the left of the centre and the other a little 

 to the right. For eyes so converging there are 

 four separate horns visible, belonging to two 

 moons which cross over each other. 



But " the poet's eye, in a fine frenzy roll- 

 ing/' as described in anticipation by another 

 poet, Shakespeare, sometimes effected the con- 

 vergence of its line of vision with that of the 

 other eye at a much nearer point, C. In this 

 plane the image for the right eye appears well 

 to the right side of the field of vision, while 

 that for the left eye appears equally far to 

 the left. As the two eyes see them in different 

 parts of their two fields, which to the brain 

 appear to be one field, the conscious vision 



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