220 ON THE EFFECTS OF CERTAIN MENTAL 



Trumpeters appeared to blow their trumpets, but no sound was 

 heard. I saw besides soldiers, people, and the forms of bodies even 

 to this day unknown to me, groves and woods, some things of which 

 I have no remembrance, and a mass of many objects rushing in toge- 

 ther, yet not with marks of confusion, but of taste." Similar to 

 this were the narrations of Blake, the painter, who saw fairies' fu- 

 nerals when he walked in groves or gardens, painted the ghosts of 

 fleas in his bed-chamber, and conversed with the shades of Homer 

 and Hesiod, Fingal, Tasso, and IMilton, in the mists of twilight, 

 on the sands and shingles of the sea shore. These instances of hal- 

 lucination appear to be dependent upon occasional or habitual men- 

 tal excitement, operating in the manner I have described. The 

 mind may be wrought to its highest pitch of agitation from feel- 

 ings partaking of a still more intense character, such as produced 

 the vision of the dagger to Macbeth. There the fear of detection — 

 the workings of a heart as yet not quite sealed in guilt — the ap- 

 prehension of failure, or detection for the murder of Duncan — and 

 the dazzling hopes which glimmered in the distance in case of suc- 

 cess ; the crown, the throne, power, and dominion with all its at- 

 tendant honour, lent their combined influence to work the mind 

 into a state of excitement which sanity could hardly equal. Mac- 

 beth's vision of the dagger is a perfect illustration of the nature of 

 these hallucinations, and his remarks upon it at once shew us that 

 he was aware that his excited state of mind had produced it. 

 Thus— 



" Art thou not, fatal vision, sensible 

 To feeling as to sight ? or art thou but 

 A dagger of the mind, a false creation 

 Springing from the heat-oppressed brain ?' 



There is, again, a particular state of mental excitement produced 

 in a mind which is occasionally the subject of aberration, upon 

 the verge of which it stands without having actually thrown 

 off the trammels of reason. It is, perhaps, superior in intensity to 

 the last ; the feeble impressions conveyed to the mind by the senses 

 are followed by ideas of the most vivid and exalted kind. Dr. Hib- 

 bert, in the zeal of metaphysical labour, has set himself to calculate 

 mathematically the direct and inverse proportion between sensations 

 and ideas, and the hallucinations which may be naturally expected 

 to follow from these states. His attempt is ingenious, but false and 

 unsatisfactory ; it is splitting hairs, and calculating with precision 



