126 NOVUM ORGANUM. 



of what relates to man ; 8. Of the preparations for inves 

 tigation ; 9. And, lastly, of the ascending and descending 

 scale of axioms. 



22. Amongst the prerogative instances we will first men 

 tion Solitary instances. Solitary instances are those which 

 exhibit the required nature in subjects that have nothing 

 in common with any other subject than the nature in ques 

 tion; or which do not exhibit the required nature in sub 

 jects resembling others in every respect except that of the 

 nature in question. For these instances manifestly remove 

 prolixity, and accelerate and confirm exclusion, so that a 

 few of them are of as much avail as many. 



For instance : let the inquiry be the nature of colour. 

 Prisms, chrystalline gems, which yield colours not only 

 internally but on the wall, dews, &c. are solitary instances. 

 For they have nothing in common with the fixed colours 

 in flowers and coloured gems, metals, woods, &c. except 

 the colour itself. Hence we easily deduce that colour is 

 nothing but a modification of the image of the incident 

 and absorbed light, occasioned in the former case by the 

 different degrees of incidence, in the latter by the various 

 textures and forms of bodies.* These are solitary instances 

 as regards similitude. 



Again, in the same inquiry, the distinct veins of white 

 and black in marble, and the variegated colours of flowers of 

 the same species, are solitary instances : for the black and 

 white of marble, and the spots of white and purple in the 

 flowers of the stock, agree in every respect but that of 

 colour. Thence we easily deduce that colour has not much 

 to do with the intrinsic natures of any body, but depends 

 only on the coarser and as it were mechanical arrange 

 ment of the parts. These are solitary instances as regards 

 difference. We call them both solitary or wild, to borrow a 

 word from the astronomers. 



23. In the second rank of prerogative instances we will 

 consider Migrating instances. In these the required nature 

 passes towards generation, having no previous existence, or 

 towards corruption, having first existed. In each of these 

 divisions, therefore, the instances are always twofold, or 

 rather it is one instance, first in motion or on its passage, 

 and then brought to the opposite conclusion. These in 

 stances not only hasten and confirm exclusion but also 



* This very nearly approaches to Sir I. Newton s discovery of the decomposi 

 tion of light by the prism. 



