NOVUM ORGANUM 157 



The difference of which we now speak is common also 

 to the nature of cold, in which the contracting motion is 

 restrained by the resistance of expansion, as in heat the ex 

 pansive motion is restrained by the resistance of contraction. 



Whether, therefore, the particles of matter penetrate 

 inward or outward, the reasoning is the same, though the 

 power be very different, because we have nothing on earth 

 which is intensely cold. 



IY. The fourth difference is a modification of the pre 

 ceding, namely, that this stimulating or penetrating motion 

 should be rapid and never sluggish, and should take place 

 not in the very minutest particles, but rather in those of 

 some tolerable dimensions. 



It is shown by comparing the effects of fire with those 

 of time. Time dries, consumes, undermines, and reduces to 

 ashes as well as fire, and perhaps to a much finer degree; 

 but as its motion is very slow, and attacks very minute 

 particles, no heat is perceived. 



It is also shown in a comparison of the dissolution of 

 iron and gold ; for gold is dissolved without the excitement 

 of any heat, but iron with a vehement excitement of it, 

 although most in the same time, because in the former the 

 penetration of the separating acid is mild, and gently in 

 sinuates itself, and the particles of gold yield easily, but 

 the penetration of iron is violent, and attended with some 

 struggle, and its particles are more obstinate. 



It is partially shown, also, in some gangrenes and morti 

 fications of flesh, which do not excite great heat or pain, 

 from the gentle nature of the putrefaction. 



Let this suffice for a first vintage, or the commencement 

 of the interpretation of the form of heat by the liberty of 

 the understanding. 



