216 Professor Necker 07i Mineralogy considered 



more complete comparison between it and the other beings exist- 

 ing in nature. 



§ 10. But although the different sciences are, when consider- 

 ed in a completely abstract point of view, essentially distinct 

 from one another, it is nevertheless true, and this remark has 

 been often alluded to in objections to the real independence of 

 the various sciences in regard to each other, that such an inde- 

 pendence is by no means so complete in practice as it may be 

 thought in theory, that all sciences are connected together by 

 common ties, and that every one of them is in need of the others 

 for attaining its particular purpose. We are far from denying 

 the fact here alluded to, but what we contend for is, that it does 

 not alter in the least what we have maintained, that the purposes 

 of the various sciences being different, the sciences must be re- 

 garded also as different. 



Natural history being obliged, in the study of individual be- 

 ings, to investigate the properties of these beings, must call to 

 aid the abstract sciences which consider abstract properties ; and 

 in this case natural philosophy and chemistry will bring their 

 abstract mode of consideration, of arrangement, &c. But here 

 they act merely as auxiliary sciences ; and if for particular and 

 subordinate purposes, natural history must momentarily bor- 

 row their language, these abstract sciences will never be allowed 

 to intrude with their methods in the principal purpose of natur- 

 al history, the description, comparison, and classification, of real 

 and positive beings. 



It is the same with chemistry. As that science is always de- 

 composing known substances, and bringing in that way new and 

 unknown bodies to light, or, by new combinations of elements, 

 forming equally new substances, it is necessary that such new- 

 bodies should be described and compared with the existing bo- 

 dies. For this subordinate and particular purpose, chemistry 

 borrows the descriptive and comparative methods of natural 

 history ; but it would never allow the natural-historical method 

 to interfere with its proper aim, which is the abstract considera- 

 tion of substances, of elementary combination. It is so true that 

 such a description of physical bodies is quite foreign to the 

 chief purpose of chemistry, that wherever such descriptions ex^ 



