i 5 S OF SLEEP. Sect. XVIII. 8. 



none of our acquired knowledge, and are hence incapable of ob- . 

 ierving any abfurclities in them. 



By this criterion we diitinguifh our waking from our fleeping 

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

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

 cannot in our fleep voluntarily recollect our waking ideas at all. 



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

 diftinctnefs of imagery, are other curious circumftances of our jj 

 ileeping 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- 

 •erable ideas j while the other fenfes collect their objects flowly, 

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

 this organ prefents us with, are more frequently connected with 

 our feniation than thofe of any other. 



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

 cumitance j the trains of ideas, which are carried on in our 

 waking thoughts, are in our dreams diflevered in a thoufand 

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

 ideas, and are hence perpetually falling into new catenations. 

 As explained in Seel:. XVI. 1. 9. For the power of volition is 

 perpetually exerted during our waking hours in comparing our 

 palling trains of ideas with our acquired knowledge of nature, 

 snd thus forms many intermediate links in their catenation. 

 And the irritative ideas excited by the flimulus of the objects, 

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

 en us, and form other links of our unceafing catenations of ideas. 



10. The abfence of the ftimuliof external bodies, and of vo- 

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

 more iirongly affected by the powers of fenfation, and of afib-i' 

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

 Tounding bodies, diffever the fenfitive and affociate tribes of 

 ideas in our waking hours by introducing thofe of irritation and 

 volition amonglt them. Hence proceeds the fuperior diftinct- 

 nefs of pleafurable or painful imagery in our ileep ; for we recat 

 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 circum (lance contributes to prove, 

 that our ideas of imagination are reiterations of thofe motions 

 of our organs of fenfe, which were excited by external objects*, 

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

 eur ideas of abfent objects cannot be fo dillinctly formed. 



11. The rapidity of the fucceflion of tranfactions in our 

 breams is almoft inconceivable •, infomuch that, when we are 

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



into 



