NOVUM ORGANUM. 331 



caution : viz. lest they should connect the Form too closely with the 

 Efficient, and so fill the Understanding, or at least tinge it, with a 

 false opinion concerning the Form, arising from the contemplation of 

 the Efficient, which is always understood to be nothing more than the 

 vehicle or bearer of the Form. But for this a remedy is provided, by 

 means of an Exclusion legitimately carried out. 



And we must now give an example of a Migrating Instance* Let 

 the Nature inquired into be Whiteness. A Migrating Instance to wards 

 generation is glass, whole and powdered ; and similarly water, at 

 rest and agitated into foam. For whole glass and plain water are 

 transparent, not white; whereas powdered glass and water in a state of 

 foam are white, and not transparent. And so inquiry must be made 

 as to what has happened to glass or water from this Migration. For 

 it is clear that the Form of Whiteness is imparted and introduced by 

 the pounding of the glass, and the agitation of the water. For we 

 find nothing has been added, except the division of the glass and 

 water into minute portions, and the introduction of air. And we 

 have made no small advance towards discovering the Form of White 

 ness, when we have found that two bodies in themselves transparent, 

 more or less, (that is to say, air and water, or air and glass), if arranged 

 together in minute portions, will exhibit Whiteness, by the unequal 

 refraction of rays of light. 



But in this matter we must also give an example of the danger and 

 caution of which we have spoken. For here, doubtless, it will readily 

 occur, to an Understanding which has been spoiled by Efficients of 

 this kind, that air is always required to produce the Form of Whiteness, 

 or that Whiteness is generated by transparent bodies only : notions 

 which are altogether incorrect, and disproved by numerous exclu 

 sions. Whereas it will appear (air and the like being left out of the 

 question) that bodies which are entirely even (in respect of those 

 portions of them which affect vision) are transparent ; but that bodies 

 which are uneven, with a simple texture, are white ; that bodies which 

 are uneven, with a compound but regular texture, assume all colours 

 except black ; but that bodies which are uneven, with a compound 

 but very irregular and confused texture, are black. And so an example 

 has now been given of a Migrating Instance towards generation in 

 the required Nature of Whiteness. And a Migrating Instance towards 

 corruption in the same Nature of Whiteness is found in foam, or in 

 snow in a state of dissolution ; for the water loses its whiteness, and 

 becomes transparent, on resuming its integral character and parting 

 with its air. 



Nor ought we by any means to overlook the fact that under the 

 head of Migrating Instances should be comprehended not only those 

 which migrate towards generation and loss, but those also which 

 migrate towards increase and decrease, since they also tend to the 

 discovery of the Form, as is sufficiently clear from the definition of 

 Form given above, and from the Table of Iifgress. Thus paper 

 which while dry is white, but when moistened (by the exclusion of air 

 and introduction of water) is less white, and approaches nearer to 



