232 ADVANCEMENT OF LEARNING. [BOOK VI. 



There are still two other limitations of propositions, be 

 sides that for making them convertible, the one for extend 

 ing and the other for producing them. For if it be just that 

 the sciences have two other dimensions, besides depth, viz. 

 length and breadth, their depth bearing relation to their 

 truth and reality, as these are what constitute their solidity; 

 their breadth may be computed from one science to another, 

 and their length fi m the highest degree to the lowest in 

 the same science, the one comprehends the ends and tru$ 

 boundaries of the sciences, whence propositions may be 

 treated distinctly J and not promiscuously, and all repetition, 

 excursion, and confusion avoided; the other prescribes a rule 

 how far and to what particular degree the propositions of 

 the sciences are to be reduced. But no doubt something 

 must here be left to practice and experience ; for men ought 

 ot avoid the extreme of Antoninus Pius, and not mince 

 cumin-seed in the sciences, nor multiply divisions to the 

 utmost. And it is here well worth the inquiry, how far we 

 should check ourselves in this respect ; for we see that too 

 extensive generals, unless they be reduced, afford little infor 

 mation, but rather expose the sciences to the ridicule of 

 practical men, as being no more fitted for practice than a 

 general map of the world to show the road from London to 

 York. The best rules may well be compared to a metalline 

 speculum, which represents the images of things, but not 

 before it is polished; for so rules and precepts are useful 

 after having undergone the file of experience. But if these 

 rules could be made exact and clear from the first, it were 



objective sciences, where, since our knowledge of the subject is general! / 

 so imperfect as to render any direct definition uncertain, we are obliged to 

 involve ourselves in a chain of reasoning to prove that the interchange 

 able attribute can be affirmed of the subject in its whole extent, and 

 that both possess no qualities which are not convertible with each other. 

 In establishing this reciprocal accordance of parts, it frequently happeni 

 that, having to connect a series of propositions in a chain of mutual 

 dependence on each other, the first being proved by the second and the 

 second by the third, &c., we arrive at and rest the whole proof upon a 

 conclusion which is nothing else than the enunciation of the very pro 

 position which we are labouring to establish, instead of grounding the 

 argument upon some universally admitted principle or well-ascertained 

 fact. This fallacy logicians term a vicious circle, and is the error t 

 wV.cb Bacon rUlwlea in the text. Ea, 



