iS8 -OF SLEEP. SECT. XVIII. g 



none of our acquired knowledge, and are hence incapable of ob~ 

 ferving any abfurdities in them. 



By this criterion we diftinguifh our waking from our fleeping 

 hours, we can voluntarily recoiled our fleeping ideas, when we 

 are awake, and compare them with our waking ones ; but we 

 cannot in our fleep voluntarily recoiled: our waking ideas at all. 



8. The vaft variety of fcenery, novelty of combination, and 

 diftindnefs of imagery, are other curious circumftances of our 

 fleeping imaginations. The variety of fcenery feems to arife 

 from the fuperior activity and excellence of our fenfe of vifion ; 

 which in an inftant unfolds to the mind extenfive fields of pleaf- 

 urable ideas ; while the other fenfes colled: their objeds flowly, 

 and with little combination ; add to this, that the ideas, which 

 this organ prefents us with, are more frequently conneded with 

 our fen fat Jon than thofe of anyotfaer, 



9. The great novelty of combination is owing to another cir- 

 cumftance $ the trains of ideas, which are carried on in our 

 waking thoughts, are in our dreams difievered in a thoufand 

 places by the iufpenflon of volition, and the abfence of irritative 

 ideas, and are hence perpetually falling into new catenations, 

 As explained in Sed. XVI. i. p. For the power of volition is 

 perpetually exerted during our waking hours in comparing our 

 parting trains of ideas with our acquired knowledge of nature, 

 and thus forms many intermediate links, in their catenation. 

 And the irritative ideas excited by the ftimulus of the objeds, 

 with which we are furrounded, are every moment intruded up- 

 on us, and form other links of our unceafmg catenations of ideas. 



10 The abfence of the flimuli of external bodies, and of vo- 

 lition, in our dreams renders the organ of fenfe liable to be 

 more flrongly affeded by the powers of fenfation, and of aflb- 

 ciation. For our defires or averfions, or the obtrufions of fur- 

 rounding bodies, diflever the fenfitive and aflbciate tribes of 

 ideas in our waking hours by introducing thofe of irritation and 

 volition amongft them. Hence proceeds the fuperior diftind- 

 nefs of pleafurable or painful imagery in our fleep ; for we recal 

 the figure and the features of a long loft friend, whom we loved, 

 in our dreams with much more accuracy and vivacity than in 

 our waking thoughts. This circumftance contributes to prove, 

 that our ideas of imagination are reiterations of thofe motions 

 of our organs of fenfe, which were excited by external objeds ; 

 becaufe while we are expofed to the ftimuli of prefent objeds, 

 our ideas of abfent objeds cannot be fo diftindly formed. 



ii. The rapidity of the fucceflion of tranfadions in our 

 dreams is almoft inconceivable ; infomuch that, when we are 

 accidentally awakened by the jarring of a door, which is opened 



into 



