138 NOVUM ORGANUM. 



stances are of great value, because they excite and keep 

 alive inquiry, and correct an understanding depraved by 

 habit, and the common course of things. 



29. In the eighth rank of prerogative instances, we will 

 place Deviating instances : such as the errors of nature, or 

 strange and monstrous objects, in which nature deviates and 

 turns from her ordinary course. For the errors of nature 

 differ from singular instances, in as much as the latter are the 

 miracles of species, the former of individuals. Their use is 

 much the same, for they rectify the understanding in oppo 

 sition to habit, and reveal common forms. For with regard 

 to these also, we must not desist from inquiry, till we dis 

 cern the cause of the deviation. The cause does not, how 

 ever, in such cases rise to a regular form, but only to the 

 latent process towards such a form. For he who is ac 

 quainted with the paths of nature, will more readily observe 

 her deviations, and vice versa, he who has learnt her devia 

 tions, will be able more accurately to describe her paths. 



They differ again from singular instances, by being much 

 more apt for practice, and the operative branch. For it 

 would be very difficult to generate new species, but less so 

 to vary known species, and thus produce many rare and 

 unusual results.* The passage from the miracles of nature 

 to those of art is easy ; for if nature be once seized in her 

 variations, and the cause be manifest, it will be easy to 

 lead her by art to such deviation as she was at first led to 

 by chance ; and not only to that but others, since deviations 

 on the one side lead and open the way to others in every 

 direction. Of this we do not require any examples, since 

 they are so abundant. For a compilation, or particular 

 natural history, must be made of all monsters and prodi 

 gious births of nature ; of every thing, in short, which is 

 new, rare, and unusual in nature. This should be done 

 with a rigorous selection, so as to be worthy of credit. 

 Those are most to be suspected which depend upon super 

 stition, as the prodigies of Livy,and those perhaps, but little 

 less, which are found in the works of writers on natural 

 magic, or even alchymy, and the like, for such men, as it 

 were, are the very suitors and lovers of fables ; but our in 

 stances should be derived from some grave and credible 

 history, and faithful narration. 



30. In the ninth rank of prerogative instances we will 



* This is well illustrated in plants, for the gardener can produce endless varie 

 ties of any known species, but can never produce a new species itself. 



