144 NOVUM ORGANUM. 



35. In the thirteenth rank of prerogative instances, we 

 will place those of Alliance or union. They are such as 

 mingle and unite natures held to be heterogeneous, and ob 

 served and marked as such in received classifications. 



These instances show that the operation and effect, which 

 is considered peculiar to some one of such heterogeneous 

 natures, may also be attributed to another nature styled 

 heterogeneous; so as to prove that the difference of the 

 natures is not real nor essential, but a mere modification of 

 a common nature. They are very serviceable, therefore, in 

 elevating and carrying on the mind, from differences to 

 genera, and in removing those phantoms and images of 

 things, which meet it in disguise in concrete substances. 



For example; let the required nature be heat. The 

 classification of heat into three kinds, that of the celestial 

 bodies, that of animals, and that of fire, appears to be 

 settled and admitted : and these kinds of heat, especially 

 one of them compared with the other two, are supposed to 

 be different, and clearly heterogeneous in their essence and 

 species, or specific nature ; since the heat of the heavenly 

 bodies and of animals generates and cherishes, whilst that of 

 fire corrupts and destroys. We have an instance of alliance 

 then in a very common experiment, that of a vine branch 

 admitted into a building where there is a constant fire, 

 by which the grapes ripen a whole month sooner than in 

 the air ; so that fruit upon the tree can be ripened by 

 fire, although this appear the peculiar effect of the sun. 

 From this beginning, therefore, the understanding rejects 

 all essential difference, and easily ascends to the investiga 

 tion of the real differences between the heat of the sun and 

 that of fire, by which their operation is rendered dissimilar, 

 although they partake of a common nature. 



These differences will be found to be four in number. 

 The heat of the sun is much milder and gentler in degree 

 than that of fire. 2. It is much more moist in quality, 

 especially as it is transmitted to us through the air. 3. 

 Which is the chief point, it is very unequal, advancing and 

 increased at one time, retiring and diminished at another; 

 which mainly contributes to the generation of bodies. For 

 Aristotle rightly asserted, that the principal cause of gene 

 ration and corruption on the surface of the earth, was the 

 oblique path of the sun in the Zodiac, whence its heat be 

 comes very unequal, partly from the alternation of night and 

 day, partly from the succession of summer and winter. Yet 

 must he immediately corrupt and pervert his discovery, by 



