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things agreeing in the middle term. d Lastly, a certain degree* 

 of sagacity in collecting and searching for physical points of 

 similarity, is very useful in many respects. 6 



XXVIII. In the seventh rank of prerogative instances, we 

 will place singular instances, which we are also wont to call 

 irregular or heteroclite (to borrow a term from the grammarians). 

 They are such as exhibit bodies in the concrete, of an apparently 

 extravagant and separate nature, agreeing but little with other 

 things of the same species. For, whilst the similar instances 

 resemble each other, those we now speak of are only like them 

 selves. Their use is much the same with that of clandestine in 

 stances : they bring out and unite nature, and discover genera or 

 common natures, which must afterwards be limited by real 

 differences. ]S T or should we desist from inquiry, until the pro 

 perties and qualities of those things, which may be deemed 

 miracles, as it were, of nature, be reduced to, and comprehended 

 in, some form or certain law; so that all irregularity or sin 

 gularity may be found to depend on some common form ; and 

 the miracle only consists in accurate differences, degree, and 

 rare coincidence, not in the species itself. Man s meditation 

 proceeds no farther at present, than just to consider things of 

 this kind as the secrets and vast efforts of nature, without an 

 assignable cause, and, as it were, exceptions to general rules. 



As examples of singular instances, we have the sun and moon 

 amongst the heavenly bodies; the magnet amongst minerals; 

 quicksilver amongst metals ; the elephant amongst quadrupeds ; 

 the venereal sensation amongst the different kinds of touch ; the 



d Bacon falls into an error here in regarding the syllogism as some 

 thing distinct from the reasoning faculty, and only one of its forms. 

 It is not generally true that the syllogism is only a form of reasoning 

 by which we unite ideas which accord with the middle term. This 

 agreement is not even essential to accurate syllogisms ; when the rela 

 tion of the two things compared to the third is one of equality or 

 similitude, it of course follows that the two things compared may be 

 pronounced equal, or like to each other. But if the relation between 

 these terms exist in a different form, then it is not true that the two 

 extremes stand in the same relation to each other as to the middle 

 term. For instance, if A is double ot B, and B double of C, then A is 

 quadruple of c. But then the relation of A to C is different from that 

 of A to B and of B to C. d. 



* Comparative anatomy is full of analogies of this kind. Those be 

 tween natural and artificial productions are well worthy of attention, 

 and sometimes lead to important discoveries. By observing an analogy 

 of this kind between the plan used in hydraulic engines for preventing 

 the counter-current of a fluid, and a similar contrivance in the blood 

 vessels, ITarvev was led to the discovery of the circulation of tbt 

 blood. Ed. 



