INTRODUCTION. Vll 



Nature occasionally produces deformities and monstrosities. Does the 

 artist, your builder, let us say, or your shipwright, never make a 

 blunder?^ Do such blunders make you infer that the artist had no 

 definite end in view ? Monstrosities are Nature's mistakes ; or, rather, 

 they are her failures ; for they are due not to any imperfection or 

 uncertainty in her action, which is invariable and faultless, but to the] 

 .un certainty of her materials. The substances in which she works are 

 of indefinite composition, and her work cannot therefore possibly be 

 uniform. The monstrosity is not Nature's work; it is the victory of 

 matter over Nature.* Thus it is that though there is nothing of hap- 

 hazard or of chance in Nature herself. Nature being invariably the 

 source of order,' yet her operations appear to be liable to exceptions, 

 and her rules to be of general rather than of universal application. 

 "In all our speculations, therefore, concerning Nature, what we have"^ 

 to consider is the genejal rule. For that is natural which holds good^ 

 either universally or generally ." * 



There is an apparent difficulty here which requires a moment's con- 

 sideration. Aristotle held the properties of the elementary forms of 

 matter to be fixed and immutable. How, then, could he explain 

 Nature's occasional miscarriages by the indefinite character of the 

 materials ? Clearly, if the properties of the elementary bodies are 

 fixed, when once an organism has been formed from them with a 

 certain degree of perfection, any failure thereafter to attain at any rate 

 to an equal degree must be attributable not to the necessary properties I 

 of matter, but to the faulty selection of material. For the properties 

 of matter manifestly cannot be inconsistent with such perfection as 

 has actually once been realised. Nature, therefore, must have been 

 held by Aristotle either to have been an influence acting with limited 

 intelligence, or to have been in some way or other hindered in her I 

 q hoice of materials ; to have had, that is, her freedom narrowed by I 

 something more than the ultimate properties of elementary matter. The 

 latter was, undoubtedly, Aristotle's view; and the limitation consisted 

 in the materials with which Nature had to deal not being the ultimate 

 elements themselves with their immutable properties, but those com- 

 pound substances which were in reality the simplest actually producible 

 bodies in existence, the pure elements themselves never being actually 

 presentable as such, in a condition, that is, of isolation.^ Had Nature 

 been able, as a modern chemist, to take so much of each or any of 

 the elementary substances as she pleased, and to form from them 

 compounds of fixed composition, and therefore of fixed properties, her 



' Phys. ii. 8, II. ^ D. G. iv. 4, 11, and iv. 10, 10, 



^ De Crelo, ii. 8, 2; Pliys. viiL i, 16 ; De CJen. iii. 10, 18, etc. 

 * D. P. iii, 2, 16. ^ Cf. ii. l, note 3. 



