PREFACE. 11 



and Avhere I have not found it, I will endeavour to find it. 

 Consequently, I can only ask a mature consideration for those 

 passages of my principles which are open to controversy, or 

 suspected of error. I am confident that there are many errors, 

 and still more defects, in this work ; but I have thought much 

 and written little, and I can therefore ask that the critics shall 

 think before they controvert. If any one would reply to any 

 of the doctrines, whether for the purpose of proving them, or 

 limiting them, or correcting misunderstandings, or refuting an 

 error, I will absolutely act only as the interests of truth re- 

 quire, and as an indifi'erent reader, who has no feeling for 

 personalities, whether they be civilities or insults, and to 

 whom no objecter exists, but only an objection. It is my 

 general rule to answer no attack on my writings, still less on 

 my character and conduct; and I willingly permit many a one 

 to use this advantage, who may think me a very troublesome 

 person to attack, and who I would not for the world should 

 know what I thought on the matter. Why should not every 

 one be at liberty to criticise another as much as he likes, if he 

 thinks him of sufficient importance ? And why should the 

 other be bound to answer him, if he do not think it of suffi- 

 cient importance to entertain the public with his justification ? 

 It is seldom that controversial writings are of any great service 

 to science ; but it is difficult to avoid explanations with a newly- 

 invented science, only a sketch of the first principles of which 

 I has appeared, not supplied with ample illustrations, without 

 any of the advantages of an introductory discourse, and with 

 the disadvantages of unusual terms and expressions, which at 

 first always excite subordinate ideas that lead the reader away 

 from the meaning of the author : thus explanations may not 

 only be required, but cannot be withheld without disadvantage 

 to the reception of the science itself. 

 I must especially ask the reader^ s forgiveness with regard to 

 these unusual terms and phrases. It will be seen that they 

 were indispensable to an accurate exposition of the ideas^ 

 without which it would be altogether impossible to give the 

 physiology of animal nature that first degree of completeness 

 which it now possesses. At one time I was not inclined to 

 seek unusual phrases; but when, two years since, I used the 

 word "feehng"' [Gefiihl] with an unusual meaning, from a 



