1. I 



BOOK I. 



(CJi. I.) Every systematic science, the humblest and the noblest 

 alike, seems to admit of two distinct kinds of proficiency ; one of 

 which may be properly called scientific knowledge of the subject, 

 while the other is a kind of ^educational acquaintance with it. 

 For an educated man should be able to form a fair offhand 

 judgment as to the goodness or badness of the method used by 

 a professor in his exposition. To be educated is in fact to be 

 able to do this ; and even the man of universal education we 

 deem to be such in virtue of his having this ability. It will, 

 however, of course, be understood that we only ascribe universal 

 education to one who in his own individual person is thus critical 

 in all or nearly all branches of knowledge, and not to one who 

 has a like ability merely in some special subject. For it is possible 

 for a man to have this competence in some one branch of know- 

 ledge without having it in all.^ 



It is plain then that, as in other sciences, so in that which enquires 

 into nature, there must be certain canons, by reference to which 

 a hearer shall be able to criticise the method of a professed expo- 

 sition, quite independently of the question whether the state- 

 ments made be true or false. Ought we, for instance, to give an 

 illustration of what I mean, to begin by discussing the specific 

 characters of each kind of animal — man, lion, ox, and the like — 

 and by describing separately the distinctive features of each, or 

 ought we rather to deal first with the characters which all these 

 animals have in common, and thus form a basis for the considera- 

 tion of them separately? For genera ^ that are quite distinct yet 

 oftentimes resemble each other in many of their phenomena ; in 

 sleep, for instance, in respiration, in growth, in decay, in death, 

 639 a. j^ 



