14 INTRODUCTION. 



pertics for the purpose of establishing a body of doctrine, and, if jiossible, of referring tlie 

 M'hule to one single law, under the universal expression of which all might be resohed. 

 Particular Physics, or Natural History, — for these terms are synonymous — has for 

 its oljjcct to apply specially the laws recognized by the various branches of General 

 Physics, to the numerous and varied beings which exist in nature, in order to explain 

 the phenomena which they severally present. 



In this extended sense, it would also include Astronomy ; but that science, suffi- 

 ciently elucidated by Mechanics, and completely subjected to its laws, employs methods 

 too different from those required by ordinary Natural History, to permit of its cultiva- 

 tion by the students of the latter. 



Natural History, then, is confined to objects wdiich do not allow of rigorous 

 calculation, or of precise measurement in all their parts. Meteorology, also, is 

 subtracted from it, to be ranged under General Physics ; so that, properly speaking, 

 it considers only inanimate bodies, called minerals, and the various kinds of living 

 beings, in all which we may observe the cft'ects, more or less various, of the laws of 

 motion and chemical attraction, and of all the other causes ani:d3'zed by General Physics. 

 Natural Historj' should, in strictness, employ the same modes of procedure as the 

 general sciences ; and it does so, in fact, whenever the objects of its study are so 

 little complex as to permit of it. But this is very seldom the case. 



An essential difference, in effect, between the general sciences and Natural Histoiy 

 is, that, in the former, phenomena are examined, the conditions of wdiicli are all 

 regulated by the examiner, in order, by their analysis, to arrive at general laws ; while 

 in the latter, they occur under circumstances beyond the control of him who studies 

 them for the purpose of discovering, amid the comjihcation, the effects of general 

 laws already known. It is not permitted for him, as in the case of the experimenter, 

 to subtract successively from each condition, and so reduce the ;iroblem to its 

 elements ; but he must take it entire, with all its conditions at once, and can analyze 

 only in thought. Suppose, for example, we attempt to isolate the numerous pheno- 

 mena wdiich compose the life of an animal a little elevated in the scale ; a single one 

 being suppressed, the life is wholly annihilated. 



Dynamics have thus become a science almost purely of calculation ; Chemistry is 

 still a science wholly [chiefly*] of experiment ; and Natural History will long remain, 

 in a great number of its branches, one of pure observation. 



These three terms sufficiently designate the modes of procedure employed in the 

 three branches of the Natural Sciences ; liut in estalilishing between them very different 

 degrees of certituile, they at the same time indicate the point to which the two latter 

 should tend, in order to approach perfection. 



Calculation, so to speak, commands Nature ; it determines phenomena more exactly 

 than observation can make them known : experiment forces her to unveil ; while obser- 

 vation watches her when deviating from her normal course, and seeks to surprise her. 



Natural History has, moreover, a principle on which to reason, which is peculiar to 

 it, and wdiich it employs advantageously on many occasions ; it is that of the conditions 

 of e.rislence, commonly termed Jinat causes. As nothing can exist without the concur- 

 rence of those conditions which render its existence possible, the component parts of each 



* The cliBcovery of llie ulomic theory has reduced iDanj' of Us plieiioniciia to ralculittion. — Ed. 



