600 KOTUM ORGANUM, [BOOK 1L 



XXXIII. In the eleventh rank of prerogative instances we 

 will place accompanying and hostile instances. These are such 

 as exhibit any body or concrete, where the required nature is 

 constantly found, as an inseparable companion, or, on the con 

 trary, where the required nature is constantly avoided, and ex 

 cluded from attendance, as an enemy. From these instances 

 may be formed certain and universal propositions, either affirma 

 tive or negative; the subject of which will be the concrete 

 body, and the predicate the required nature. For particular 

 propositions are by no means fixed, when the required nature is 

 found to fluctuate and change in the concrete, either approaching 

 and acquired, or receding and laid aside. Hence particular pro 

 positions have no great prerogative, except in the case of migra 

 tion, of which we have spoken above. Yet such particular Dro- 

 positions are of great use, when compared with the universal, as 

 will be mentioned in its proper place. Nor do we require ab 

 solute affirmation or negation, even in universal propositions, for 

 if the exceptions be singular or rare, it is sufficient for our pur 

 pose. 



The use of accompanying instances is to narrow the affirmative 

 of form ; for as it is narrowed by the migrating instances, where 

 the form must necessarily be something communicated or de 

 stroyed by the act of migration, so it is narrowed by accompany 

 ing instances, where the form must necessarily be something which 

 enters into the concretion of the body, or, on the contrary, is 

 repugnant to it ; and one who is well acquainted with the con 

 stitution or formation of the body, will not be far from bringing 

 to light the form of the required nature. 



For example : let the required nature be heat. Flame is an 

 accompanying instance ; for in water, air, stone, metal, and many 

 other substances, heat is variable, and can approach or retire ; 

 but all flame is hot, so that heat al ways accompanies the concre 

 tion of flame. \Ve have no hostile instance of heat ; for the 

 senses are unacquainted with the interior of the earth, and there 

 is no concretion of any known body which is not susceptible of 

 heat. 



Again, let solidity be the required nature. Air is an hos 

 tile instance: for metals may be liquid or solid, so may glass; 

 even water may become solid by congelation, but air cannot 

 become solid or lose its fluidity. 



With regard to these instances of fixed propositions, there are 

 two points to be observed, which are of importance. First, that 

 if there be no universal affirmative or negative, it be carefully 

 noted as not existing. Thus, in heat, we have observed that there 

 exists no universal negative, in such substances, at least, as have 

 come to our knowledge. Again, if the required nature be eter 

 nity or ineomiptibilitv, we have po universal affirmative within 



