317 



CHAP. II. 



IMPORTANCE OF ACQUIRING FIRST PRINCIPLES. REASONS FOR 



SUPPOSING A PLAN IN CREATION. OPINIONS THEREON. 



THE CIRCULAR THEORY, AND THE DIFFERENT TESTS WHICH 

 EVERY CIRCLE MUST UNDERGO, EXPLAINED AND ILLUSTRATED. 



(383.) IN the foregoing chapter we have laid before 

 the student the qualifications which should be possessed 

 both by the practical and the scientific naturalist ; and, 

 having stated the objects of the former, we must now 

 turn to the latter ; with the hope that the reader has both 

 the time and disposition to acquire more than a super- 

 ficial knowledge of zoology ; and that he is more de- 

 sirous of pursuing it as a science, than to rest contented 

 with being a mere collector of objects and facts. It has 

 hitherto been but little the custom, with the inventors of 

 systems, to lay before their disciples the reasons which 

 have guided them ; it being generally taken for granted 

 that the reputation of the writer rendered such a step 

 unnecessary. It seldom happens, indeed, that students 

 desire such information ; for if, from whatever cause, 

 they resolve to adopt any particular system not connected 

 with general principles, they trouble not themselves with 

 seeking to know and to criticise the reasons upon which 

 a system is founded. It is received by them as a law, 

 propagated by a ruler of science, which they have 

 neither the disposition nor the knowledge to call in 

 question. This feeling continues, until they acquire 

 sufficient knowledge to discover the defects (real or 

 imaginary) of their favourite oracle. It is then that the 

 desire arises to know the reasons which have influenced 

 the author, and the principles, if any, upon which he has 

 proceeded. The student, in the mean time, has probably- 

 become an adept, and feels himself qualified to criticise 

 that which, at the commencement of his studies, he 



