39 g BACON 



For example, let heat be the required nature. The thermom- 

 eter is a conspicuous instance of the expansive motion, which 

 (as has been observed) constitutes the chief part of the form of 

 heat ; for although flame clearly exhibits expansion, yet from 

 its being extinguished every moment, it does not exhibit the 

 progress of expansion. Boiling water again, from its rapid con- 

 version into vapor, does not so well exhibit the expansion of 

 water in its own shape, whilst red-hot iron and the like are so 

 far from showing this progress that, on the contrary, the ex- 

 pansion itself is scarcely evident to the senses, on account of its 

 spirit being repressed and weakened by the compact and coarse 

 particles which subdue and restrain it. But the thermometer 

 strikingly exhibits the expansion of the air as being evident 

 and progressive, durable and not transitory. 



Take another example. Let the required nature be weight. 

 Quicksilver is a conspicuous instance of weight ; for it is far 

 heavier than any other substance except gold, which is not 

 much heavier, and it is a better instance than gold for the pur- 

 pose of indicating the form of weight; for gold is solid and 

 consistent, which qualities must be referred to density, but 

 quicksilver is liquid and teeming with spirit, yet much heavier 

 than the diamond and other substances considered to be most 

 solid ; whence it is shown that the form of gravity or weight 

 predominates only in the quantity of matter, and not in the close 

 fitting of it. 



25. In the fourth rank of prerogative instances we will class 

 clandestine instances, which we are also wont to call twilight 

 instances; they are, as it were, opposed to the conspicuous 

 instances, for they show the required nature in its lowest state 

 of efficacy, and as it were its cradle and first rudiments, making 

 an effort and a sort of first attempt, but concealed and subdued 

 by a contrary nature. Such instances are, however, of great 

 importance in discovering forms, for as the conspicuous tend 

 easily to differences, so do the clandestine best lead to genera, 

 that is, to those common natures of which the required natures 

 are only the limits. 



As an example, let consistency, or that which confines itself, 

 be the required nature, the opposite of which is a liquid or flow- 

 ing state. The clandestine instances are such as exhibit some 

 weak and low degree of consistency in fluids, as a water bubble, 

 which is a sort of consistent and bounded pellicle formed out of 

 the substance of the water. So eaves' droppings, if there be 

 enough water to follow them, draw themselves out into a thin 

 thread, not to break the continuity of the water, but if there be 

 not enough to follow, the water forms itself into a round drop, 

 which is the best form to prevent a breach of continuity ; and 

 at the moment the thread ceases, and the water begins to fall 



