270 AN TIE NT METAPHYSICS. Book IV. 



of it, and If our Mind is free from paifions and perturbations, and 

 very much employed in philofophical fpeculations, I have no doubt 

 of the truth of what Plato fays*, that Sleep will not much interrupt 

 our progrefs in fcience. 



I come now, at laft, to what is the fubjeft of this Chapter, viz. 

 Dreams, properly fo called ; and I am hopeful, that fo long an In- 

 trodudlion to the fubject will not appear unneceflary or fuperfluous : 

 And, if I am not miftaken, from what I have faid, I Ihall be able, 

 not only to explain the fadls concerning Dreaming, but to demon- 

 ftrate, a priori, that they muft have exifted ; for the confequence of 

 an accurate inveftigation of any queftlon of natural philofophy is, 

 that, by reafoning a pojleriori^ we difcover principles, from which 

 we are able, by reafoning a priori, to deduce the phaenomena. 

 And this, I truft, has happened in the prefent cafe. 



And, in the jJV/? place, as the Animal Life in us is an Immaterial 

 Subftance, and, confequently, an adive Principle, though it be qui- 

 efcent in the womb, and not perfect even when we are born, but, 

 like other things in nature, coming to perfedlion by degrees, I hold 

 it to be certain, that, when both the Body and it are arrived to a 

 ftate of maturity, it will not require that reft which, we ar^fure, the 

 Body and its Organs require. Although, therefore, I am inclined 

 to believe, that neither the Animal nor the Intelledual Principle is 

 perpetually adlive while clogged and incumbered with this Body ; yet 

 I think it impoflible to believe that our Intellecftual part will be fo 

 foon tired with thinking, or our animal part in operating upon the 

 forms in our Phantafia, as the Body is with Motion, the Eye in See- 

 ing, the Ear with Hearing, or the Nerves, which are fuppofed ta 

 convey thefe Senfations to the Brain, in performing their functions. 



And, 



* De Rep. Lib. 9. in initio. 



