152 SPECTRES OCCASIONED BY DISEASE. 



however, have by no means confidered that arbitrary fyftematic 

 divifions, do not conftitute an inveftigation of nature, and that 

 They are of philofophy often becomes raore uncertain the more precifely 

 httle ufe, ^g endeavour to diftinguidi and feparate what nature has 



clofely united. Sub-divifions in fpeculation feem as neceflary 

 as fences in fields, both are in themfelves unproduftive, and 

 the more they are multiplied and extended the greater is the- 

 diminution of the fertility, 

 and quite Inac- For my part, I will confefs, that J do not know where the 

 turate. corporeal ertence in man ceafes, or where the mental begins ; 



though I admit of the diftinftion, becaufe the extreme differ- 

 ences can be clearly perceived. If we divide man into three 

 parts, we (hall be far from removing the difficulties, as we 

 fliould be were we even to follow thofe modern philofophers, 

 who regard the thinking fubje6t alone as the real Being {Ego,l 

 and confider all external appearances as confined to the ideas 

 of confcious beings. The greateft and moft peculiar difficul- 

 ties in the philofophic knowledge of the human fubjeft confifts 

 in (his, that we have never yet been able clearly and diftindlly 

 to afcertain the internal aflbciation of thofe ftriking diflferences 

 which we obferve in our being. Neither the moft fubtil phy- 

 fiology nor the fineft fpeculative philofophy, have yet been able 

 Speculations on to explain the union of thought and phyfical operations. We may 

 the nature of indeed doubt whether the labours of our German philofophers, 

 4clufive. though founded jointly upon modern fpeculation and modern 



chemiftry, will be attended with any greater fuccefs. Extreme 

 caution is moft undoubtedly requifite to prevent our becoming 

 too intimately and habitually acquainted with certain hypothe- 

 tical notions refpe6ling things really unknown, fo as to miftake 

 them for truths and deduce erroneous conclufions. 



It is much to be feared that the hypothefes and poftulates of 

 fpeculation will be of little value in this cafe ; though to us they 

 may feem very confiftent and clear, while we regard them only 

 in a certain point of view. An attention to experimental proof 

 may bring us nearer to our aim, though its perfe6l accomplifh- 

 ment will perhaps never be within the reach of human invefti- 

 gation. Experiments or fa6ls may (hew the corporeal as well 

 as the mental fundions in feveral lights, and in fuch as we 

 never can perceive by mere fpeculation. 

 Advantages of Though it is truly faid that the firft principles of nature are 

 tcfe^rch. placed beyond our reach, yet an endeavour to penetrate into 



the 



