NOVUM ORGANUM 167 



by the interposition of the air, as to admit of being thrown 

 some little distance without bursting. The best example is 

 that of froth and snow, which assume such consistency as 

 almost to admit of being cut, although composed of air and 

 water, both liquids. All these circumstances clearly show 

 that the terms liquid and consistent are merely vulgar no 

 tions adapted to the sense, and that in reality all bodies have 

 a tendency to avoid a breach of continuity, faint and weak 

 in bodies composed of homogeneous parts (as is the case with 

 liquids), but more vivid and powerful in those composed of 

 heterogeneous parts, because the approach of heterogeneous 

 matter binds bodies together, while the insinuation of homo 

 geneous matter loosens and relaxes them. 



Again, to take another example, let the required nature 

 be attraction or the cohesion of bodies. The most remark 

 able conspicuous instance with regard to its form is the mag 

 net. The contrary nature to attraction is non-attraction, 

 though in a similar substance. Thus iron does not attract 

 iron, lead lead, wood wood, nor water water. But the clan 

 destine instance is that of the magnet armed with iron, or 

 rather that of iron in the magnet so armed. For its nature 

 is such that the magnet when armed does not attract iron 

 more powerfully at any given distance than when unarmed; 

 but if the iron be brought in contact with the armed magnet, 

 the latter will sustain a much greater weight than the simple 

 magnet, from the resemblance of substance in the two por 

 tions of iron, a quality altogether clandestine and hidden in 

 the iron until the magnet was introduced. It is manifest, 

 therefore, that the form of cohesion is something which is 

 vivid and robust in the magnet, and hidden and weak in the- 

 iron. It is to be observed, also, that small wooden arrows 

 without an iron point, when discharged from large mortars, 



