344 NOVUM ORGANUM. 



senses, while of those bodies which we do know there is not a single 

 concretion which is not susceptible of heat. 



Again, let the Nature inquired into be Consistency. A Hostile 

 Instance is Air. For metal may be fluid, and also possess consistency ; 

 the same is the case with glass ; water also can possess consistency 

 when it is frozen ; but it is impossible that air can ever possess con 

 sistency, or put off its fluidity. 



But with regard to such Instances of Fixed Propositions there remain 

 two warnings which are of use for the matter in hand. The first 

 is, that if a Universal Affirmative or Negative be wanting, that very 

 thing should be diligently marked as non-existent ; as we have done 

 concerning heat, where the Universal Negative (as far as regards the 

 essences which have come to our knowledge) is wanting in the 

 Nature of things. Similarly, if the Nature inquired into be Eternity 

 or Incorruptibility, we have here no Universal Affirmative. For 

 eternity or incorruptibility cannot be predicated of any of those bodies 

 which are beneath the heavens, and above the interior of the earth. 

 The other warning is, that to Universal Propositions, Affirmative or 

 Negative, concerning any concrete, there should be subjoined at the 

 same time those concretes which seem to approach most nearly to 

 that which is non-existent ; as in heat, the most gentle and least 

 scorching flames ; in incorruptibility, gold, which comes nearest it. 

 For all such indicate the limits of Nature between the existent and the 

 non-existent ; and help to circumscribe Forms, by hindering them 

 from spreading and wandering beyond the conditions of matter. 



xxxiv. Among Prerogative Instances we shall put in the twelfth 

 place, those same Subjunctive Instances concerning which we spoke 

 in the foregoing Aphorism, which we also call Ultimate or Limiting 

 Instances. For Instances of this kind are not only useful when sub 

 joined to fixed propositions, but also by themselves, and in their own 

 proper Nature ; for they indicate, not obscurely, the true divisions of 

 Nature and measures of things, and how far Nature may do and 

 endure in any case ; and then her passage to something else. Such 

 are, gold in weight, iron in hardness, the whale in size among animals, 

 the dog in scent, the inflammation of gunpowder in rapid expansion, 

 and other things of that kind. Nor should those things which are 

 extreme in the lowest degree be less noticed than those which are 

 extreme in the highest ; as spirit of wine in weight, silk in softness, 

 the worms of the skin in size of animal, &c. 



xxxv. Among Prerogative Instances we shall place in the thirteenth 

 place, Instances of Alliance or Union. They are those which mingle 

 and unite Natures which are thought to be heterogeneous, and as 

 such are marked and designated by the received divisions. 



Now, Instances of Alliance show that the operations and effects 

 which are set down as peculiar to some one of those heterogeneous 

 Natures belong also to others ; so that what is supposed to be hete 

 rogeneous is proved to be such neither really nor essentially, but only 

 a common Nature modified. And so they are of excellent use in 

 elevating and raising the Understanding from differences to genera, 



