ANALOGY. 103 



known origin, may resemble, in certain of its charac- 

 ters, known works of a particular master, but in 

 others it may as strikingly resemble productions 

 known not to be his. A vase may bear some analogy 

 to works of Grecian, and some to those of Etruscan, 

 or Egyptian art. We are of course supposing that it 

 does not possess any quality which has been ascer- 

 tained, by a sufficient induction, to be a conclusive 

 mark either of the one or of the other. 



3. Since the value of an analogical argument 

 inferring one resemblance from other resemblances 

 without any antecedent evidence of a connexion 

 between them, depends upon the extent of ascertained 

 resemblance, compared first with the amount of ascer- 

 tained difference, and next with the extent of the 

 unexplored region of unascertained properties ; it fol- 

 lows that where the resemblance is very great, the 

 ascertained difference very small, and our knowledge 

 of the subject-matter tolerably extensive, the argu- 

 ment from analogy may approach in strength very 

 near to a valid induction. If, after much observation 

 of B, we find that it agrees with A in nine out of ten 

 of its known properties, we may conclude with a 

 probability of nine to one, that it will possess any 

 given derivative property of A. If we discover, for 

 example, an unknown animal or plant, resembling 

 closely some known one in the greater number of the 

 properties we observe in it, but differing in some few, 

 we may reasonably expect to find in the unobserved 

 remainder of its properties, a general agreement with 

 those of the former ; but also a difference, correspond- 

 ing proportionally to the amount of observed diver- 

 sity. 



It thus appears that the conclusions derived from 



