NOVUM ORGANUM 427 



means of that which lies at the surface, or proceeds from the 

 interior ; thus the state of the body is judged of by the pulse, 

 urine, etc. 



The third and fourth cases apply to many subjects, and the 

 reduction to the sphere of the senses must be obtained from 

 every quarter in the investigation of things. There are many 

 examples. It is obvious that air, and spirit, and the like, whose 

 whole substance is extremely rare and delicate, can neither be 

 seen nor touched a reduction, therefore, to the senses becomes 

 necessary in every investigation relating to such bodies. 



Let the required nature, therefore, be the action and motion 

 of the spirit enclosed in tangible bodies ; for every tangible body 

 with which we are acquainted, contains an invisible and in- 

 tangible spirit, over which it is drawn, and which it seems to 

 clothe. This spirit being emitted from a tangible substance, 

 leaves the body contracted and dry ; when retained, it softens 

 and melts it ; when neither wholly emitted nor retained, it 

 models it, endows it with limbs, assimilates, manifests, organ- 

 izes it, and the like. All these points are reduced to the sphere 

 of the senses by manifest effects. 



For in every tangible and inanimate body the enclosed spirit 

 at first increases, and as it were feeds on the tangible parts 

 which are most open and prepared for it; and when it has 

 digested and modified them, and turned them into spirit, it 

 escapes with them. This formation and increase of spirit is 

 rendered sensible by the diminution of weight ; for in every 

 desiccation something is lost in quantity, not only of the spirit 

 previously existing in the body, but of the body itself, which 

 was previously tangible, and has been recently changed, for 

 the spirit itself has no weight. The departure or emission of 

 spirit is rendered sensible in the rust of metals, and other putre- 

 factions of a like nature, which stop before they arrive at the 

 rudiments of life, which belong to the third species of process. 

 In compact bodies the spirit does not find pores and passages 

 for its escape, and is therefore obliged to force out, and drive 

 before it, the tangible parts also, which consequently protrude, 

 whence arises rust and the like. The contraction of the tan- 

 gible parts, occasioned by the emission of part of the spirit 

 (whence arises desiccation), is rendered sensible by the in- 

 creased hardness of the substance, and still more by the fis- 

 sures, contractions, shrivelling, and folds of the bodies thus 

 produced. For the parts of wood split and contract, skins be- 

 come shrivelled, and not only that, but, if the spirit be emitted 

 suddenly by the heat of the fire, become so hastily contracted 

 as to twist and roll themselves up. 



On the contrary, when the spirit is retained, and yet ex- 

 panded and excited by heat or the like (which happens in solid 



