642 NOVUM ORGANUM. [bOOK H 



little to "be wondered at, since Leaven and eartli are always 

 present, whilst the causes and sources of many other motions 

 are sometimes absent and sometimes present. They therefore 

 called this perpetual and proper, because it is never interrupted, 

 but instantly takes place when the others are interrupted, and 

 they called the others adscititious. The former, however, is in 

 reality weak and slow, since it yields, and is inferior to the 

 others as long as they act, unless the mass of the body be great; 

 and although this motion have so tilled men's minds, as almost 

 to have obscured all others, yet tliey know but little about it, 

 and commit many errors in its estimate. 



Let the eighth be that which we term the motion of lesser 

 congregation, by which the homogeneous parts in any body 

 separate themselves from the heterogeneous and unite together, 

 and whole bodies of a similar substance coalesce and tend 

 towards each other, and are sometimes congregated, attracted, 

 and meet, from some distance ; thus in milk the cream rises after 

 a certain time, and in wine the dregs and tartar sink ; which 

 effects are not to be attributed to gravity and levity only, so as 

 to account for the rising of some parts and the sinking of otliers, 

 but much more to the desire of the homogeneous bodies to meet 

 and unite. This motion differs from that of need in two points : 

 1st, because the latter is the stimukis of a malignant and con- 

 trary nature, whilst in this of wliicli we .treat (if there be no 

 impediment or restraint), the parts are united by their afBnity, 

 although there be no foreign nature to create a struggle ; 2ndly, 

 because the union is closer and more select. For in the other 

 motion, bodies which have no great affinity unite, if they can 

 but avoid the hostile body, whilst in this, substances wdiich are 

 connected by a decided kindred resemblance come together and 

 are moulded into one. It is a motion existing in all compound 

 bodies, and would be readily seen in each, if it were not confined 

 and checked by the other affections and necessities of bodies 

 which disturb the union. 



This motion is usually confined in the three following manners : 

 by the torpor of the bodies ; by the power of tlie predominating 

 body ; by external motion. With regard to the first, it is 

 certain tliat there is more or less sluggishness in tangible bodies, 

 and an abhorrence of locomotion ; so that unless excited they 

 prefer remaining contented with their actual state, to placing 

 themselves in a better position. There are three means of 

 breaking through this sluggishness, — heat ; the active power of a 

 similar body ; vivid and powerful motion. With regard to the 

 first, heat is, on this account, defined as that which separates 

 heterogeneous, and draws together homogeneous substances ; a 

 definition of the Peripa.tsstics which is justly ridiculed by Gilbert, 

 who says it is as ^f on.s were fco define mm to be that whicl^ 



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