ANALOGY. 



which and the earth there is a much closer resemblance ; which 

 possess an atmosphere, clouds, consequently water (or some 

 fluid analogous to it), and even give strong indications of 

 snow in their polar regions ; while the cold, or heat, though 

 differing greatly on the average from ours, is, in some parts 

 at least of those planets, possibly not more extreme than in 

 some regions of our own which are habitable. To balance 

 these agreements, the ascertained differences are chiefly in the 

 average light and heat, velocity of rotation, density of material, 

 intensity of gravity, and similar circumstances of a secondary 

 kind. With regard to these planets, therefore, the argument 

 of analogy gives a decided preponderance in favour of their 

 resembling the earth in any of its derivative properties, such 

 as that of having inhabitants ; though, when we consider how 

 immeasurably multitudinous are those of their properties which 

 we are entirely ignorant of, compared with the few which we 

 know, we can attach but trifling weight to any considerations 

 of resemblance in which the known elements bear so incon 

 siderable a proportion to the unknown. 



Besides the competition between analogy and diversity, 

 there may be a competition of conflicting analogies. The new 

 case may be similar in some of its circumstances to cases in 

 which the fact in exists, but in others to cases in which it is 

 known not to exist. Amber has some properties in common 

 with vegetable, others with mineral products. A painting of 

 unknown origin, may resemble, in certain of its characters, 

 known works of a particular master, but in others it may as 

 strikingly resemble those of some other painter. 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 ascertained, 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 ante 

 cedent evidence of a connexion between them, depends on the 

 extent of ascertained resemblance, compared first with the 



