244 THE EOYAL INSTITUTION. [CHAP. IV. 



incidence of theories with visible effects, and because objects 

 of sense are of advantage in assisting the imagination to 

 comprehend, and the memory to retain, what in a more 

 abstracted form might fail to excite sufficient attention. 

 With regard to the mode of delivering these lectures, I 

 shall in general entreat my audience to pardon the 

 formality of a written discourse in favour of the advantage 

 of a superior degree of order and perspicuity. It would 

 unquestionably be desirable that every syllable advanced 

 should be rendered perfectly easy and comprehensible even 

 to the most uninformed, that the most inattentive might 

 find sufficient variety and entertainment in what is sub- 

 mitted to them to excite their curiosity, and that in all 

 cases the pleasing, and sometimes even the surprising, should 

 be united with the instructive and the important. But, 

 whenever there appears to be a real impossibility of re- 

 conciling these various objects, I shall esteem it better to 

 seek for substantial utility than temporary amusement ; 

 for if we fail of being useful, for want of being sufficiently 

 popular, we remain at least respectable ; but if we are un- 

 successful in our attempts to amuse, we immediately appear 

 trifling and contemptible. It shall, however, at all times be 

 my endeavour to avoid each extreme, and I trust that I 

 shall then only be condemned when I am found abstruse 

 from ostentation or uninteresting from supineness. The 

 most difficult thing for a teacher is to recollect how much 

 it cost himself to learn, and to accommodate his instruction 

 to the apprehension of the uninformed. By bearing in mind 

 this observation I hope to be able to render my lectures 

 more and more intelligible and familiar, not by passing 

 over difficulties, but by endeavouring to facilitate the task 

 of overcoming them ; and if at any time I appear to have 

 failed in this attempt, I shall think myself honoured by any 

 subsequent inquiries that my audience may be disposed to 

 make. 



The division of the whole course of lectures into three 



