ITS DIVISIONS MUST ADVANCE TOGETHER. 225 



to be constantly related to the greatest number of other 

 like peculiarities. And similarly in zoology, the successive 

 classifications, from having been originally determined by 

 external and often subordinate characters not indicative of 

 the essential nature, have been gradually more and more 

 determined by those internal and fundamental differences, 

 which have uniform relations to the greatest number of other 

 differences. Nor shall we besui-prised at this analogy bet ween 

 the modes of progress of positive science and classification, 

 when we bear in mind that both proceed by making gener 

 alizations ; that both enable us to make previsions differing 

 only in their precision ; and that while the one deals with 

 equal properties arid relations, the other deals with proper 

 ties and relations that approximate towards equality in var 

 iable degrees. 



Without further argument, it will, we think, be suffi 

 ciently clear that the sciences are none of them separately 

 evolved are none of them independent either logically or 

 historically ; but that all of them have, in a greater or less 

 degree, required aid and reciprocated it. Indeed, it needs 

 but to throw aside theses, and contemplate the mixed char 

 acter of surrounding phenomena, to at once see that these 

 notions of division and succession in the kinds of knowledge 

 are none of them actually true, but are simple scientific 

 fictions - good, if regarded merely as aids to study ; bad, 

 if regarded as representing realities in Nature. Consider 

 them critically, and no facts whatever are presented to our 

 senses uncombined with other facts no facts whatever but 

 are in some degree disguised by accompanying facts : 

 disguised in such a manner that all must be partially under 

 stood before any one can be understood. If it be said, as 

 by M. Comte, that gravitating force should be treated of 

 before other forces, seeing that all things are subject to it, 

 it may on like grounds be said that heat should be first 

 dealt with ; seeing that thermal forces are everywhere in 



