386 MEMOIR OF HAUY. 



organized beings, it was forgotten that in mineralogy the principle is 

 wanting which has given birth to the idea of species, namely, that of 

 generation ; and that even the principle of individuality is scarcely 

 admissible, when our conception of it is founded, as in the organic 

 world, on a unity of action among different organs concurring to the 

 support of a single life. 



It is not by the material that the identity of species in plants and 

 animals manifests itself, but by the form, as the name of the species 

 itself indicates. No two men, perhaps, nor oaks, nor roses, have the 

 substances which compose their material in the same proportions ; and 

 even those substances are in a state of incessant change: they circulate 

 rather than reside within that abstract space and outline which we call 

 the form of the object. In a few years there will remain, perhaps, not 

 not an atom of what composes our body to-day. It is the form alone 

 which is permanent, and which, transmitted by the mysterious process 

 of generation, will continue to attract to itself, through an endless suc- 

 cession of individuals, molecules as different in their source as transitory 

 in their condition. 



On the contrary, in minerals, where there is no apparent movement, 

 where the molecules remain fixed until separated by some external 

 force ; where the material, in a word, is permanent, it would seem at 

 the first glance that this', or in other terms the. chemical composition, 

 ought to constitute the essence of the thing. But reflection teaches us 

 that if the things themselves are different, this can scarcely happen 

 except through the form of their molecules ; that from the peculiar form 

 of these molecules, and their respective mode of grouping, there must 

 necessarily result determinate forms in the mass ; and that in miner- 

 alogy, if there is anything which can represent the individual, it must 

 be those resulting forms when they exhibit a regular whole ; that is to 

 say, a crystal; since at the moment, at least, when this crystal came 

 together, all its constituent molecules must have concurred in a common 

 movement and grouped themselves by the force of some common law. 

 Now, nothing proves that in this common movement particles of a 

 different nature which happened to be within the same sphere of action 

 may not have been involved in it, nor that elements or atoms identical 

 in their nature may not, at the moment of contracting their original 

 union, have grouped themselves into different crystallized molecules. 

 But that which the mind conceives as possible, experience has taught 

 us to be real ; whence, it is evident that, in these two cases, chemical 

 analysis would give but an incomplete idea of the mineral, and one not 

 at all in accordance with those of its properties which are most obvious. 



Such are the views, doubtless, which, without being very distinctly 

 taken into account by Haiiy himself, guided his genius, or, if the ex- 

 pression be preferred, his scientific instinct, and led him to assign 

 -.crystallization the first rank in his determinations of mineralogical 

 species. 



All the discoveries and observations since made, even those which 

 have been looked upon as objections to this fundamental rule, may be 

 said rather to be confirmations of it. Thus, for example, Avhat has 

 been just said of the crystallizing force and its power of engaging other 

 molecules with the essential ones, is so true that the former are attracted 



