BOOK II.] CO:,'SPICUOUS INSTANCES 485 



compound but regular texture all the other colours except black, 

 but those which are uueven and of a compound irregular and 

 confused texture exhibit blackness. An example has been given, 

 therefore, of an instance migrating towards generation in the 

 required nature of whiteness. An instance migrating towards 

 corruption in the same nature is that of dissolving froth or snow. 

 for they lose their whiteness and assume the transparency of 

 water in its pure state without air. 



Nor should we by any means omit to state, that under mi- 

 grating instances we must comprehend not only those which 

 pass towards generation and destruction, but also those which 

 pass towards increase or decrease, for they, too, assist in the dis- 

 covery ot the form, as is clear from our definition of a form and 

 the Table of Degrees. Hence paper, which is white when dry, 

 is less white when moistened (from the exclusion of air and ad- 

 mission of water), and tends more to transparency. The reason 

 is the same as in the above instances." 



XXIV. In the third rank of prerogative instances we will 

 class conspicuous instances, of which we spoke in our first vin- 

 tage of the form of heat, and which we are also wont to call co- 

 ruscations, or free and predominant instances. They are such 

 as show the required nature in its bare substantial shape, and at 

 its height or greatest degree of power, emancipated and free 

 from all impediments, or at least overcoming, suppressing, and 

 restraining them by the strength of its qualities; for since every 

 body is susceptible of many united forms of natures in the con- 

 crete, the consequence is that they mutually deaden, depress, 

 break, and confine each other, and the individual forms are 

 obscured. But there are some subjects in which the required 

 nature exists in its full vigour rather than in others, either froni 

 the absence of any impediment, or the predominance ol its qua- 

 lity. Such instances are eminently conspicuous. But even in 

 these care must be taken, and the hastiness of the understanding 

 checked, for whatever makes a show of the form, and forces it 

 forward, is to be suspected, and recourse must be had to severe 

 and diligent exclusioc. 



For example, let heat be the required nature. The thermo- 

 meter is a conspicuous instance of the expansive motion, which 

 (as has been observed) constitutes the chief part of the form of 

 heat; for although flame clearly exhibits expansion, yet from its 

 being extinguished every moment, it does not exhibit the pro- 

 gress of expansion. Boiling water again, from its rapid conver- 



» The mineral kingdom, as displaying the same nature in all its gra- 

 dations, from the shells so perfect in structure in limestone to the finer 

 marbles in which their nature gradually disappears, is the ffie^t Vieatrf 

 fur iastaaces gi migration, ^'W, 



