NOVUM ORGANUM 189 



tied 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, while 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 con 

 stant 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 

 investigation 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. 

 1. 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 gen 

 eration 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 dictating to nature according to his habit, and dogmati 

 cally assigning the cause of generation to the approach of 



