INTRODUCTORY REMARKS. 11 



Take for instance the Ptolemaic System, which we may 

 almost literally explain by the expression of Shakspeare : 

 * He that is giddy thinks the world turns round/ We now 

 see the error of this system, because we have all an immedi- 

 ate opportunity of refuting it ; but this identical error was 

 received as a truth for centuries, because, when first promul- 

 gated, the means of refuting it were not at hand, and when 

 the means of its refutation became attainable, mankind had 

 been so educated to the supposed truth, that they rejected the 

 proof of its fallacy. 



I have premised the above for two reasons : first to obtain 

 a fair hearing, by requesting as far as possible a dismissal 

 from the mind of my readers of preconceived views by and in 

 favour of which all are liable to be prejudiced ; and secondly, 

 to defend myself from the charge of undervaluing authority, 

 or treating lightly the opinions of those to whom and to 

 whose memory mankind looks with reverence. Properly to 

 value authority, we should estimate it together with its means 

 of information : if ' a dwarf on the shoulders of a giant can 

 see further than the giant/ he is no less a dwarf in compari- 

 son with the giant. 



The subject on which I am about to treat viz., the rela- 

 tion of the affections of mattei to each other and to matter 

 peculiarly demands an unprejudiced regard. The different 

 aspects under which these agencies have been contemplated ; 

 the different views which have been taken of matter itself ; 

 the metaphysical subtleties to which these views unavoidably 

 lead, if pursued beyond fair inductions from existing expe- 

 rience, present difficulties almost insurmountable. 



The extent of claim which my views on this subject may 

 have to originality has been stated in the Preface ; they be- 

 came strongly impressed upon my mind at a period when I 

 was much engaged in experimental research, and were, as I 

 then believed, and still believe, regarding them as a system, 

 new : expressions in the works of different authors, bearing 



