Vlll INTRODUCTION. . 



operations would have had a fixed basis, and her invariable purposes 

 have been carried out with invariable precision. But, in making earthly 

 organisms, she had to deal with materials as they actually exist on 

 iearth ; and such were of in^temiinate composition,^ and therefore of 

 indeterminate properties. For it must be borne in mind that though 

 Aristotle distinguished chemical union from mere mechanical inter- 

 mixture,'^ he had of course no notion either of combination in definite 

 proportions, or even of preferential affinities. There was no such thing 

 as definite composition, or definite compound substances. One piece 

 of compound matter might more or less nearly resemble another, but 

 that it should be identical with it in composition, and therefore in 

 properties, was in the infinity of possibilities not to be dreamed of. 

 Every sample of material would differ more or less from every other ; and 

 organisms made from such materials could never be precisely alike. The 

 heavenly bodies being formed of a single pure uncombined elementary 

 substance were free from such variability, and their phenomena were 

 therefore absolutely fixed and eternal. But earthly substances were all 

 compound, and therefore all indeterminate. Their compound character 

 introduced an element of chance, which often thwarted Nature's efforts, 

 the faulty matter refusing to take the form she would impress upon it. 



There is a question to which one would gladly find an answer, but 

 to which no sure answer is forthcoming. Did Aristotle suppose that there 

 stood anything in the background behind this mysterious organising 

 force which he personified as Nature ? And, if so, what was it ? That 

 the force which constrained the material of each individual organism 

 to develop into the form most suited to the requirements was the same 

 force which, acting on a larger scale, brought the fishes of the sea, the 

 fowls of the air, the plants of the earth, and in short all forms of life, 

 more or less completely into harm onious relations with each other,' 

 and established an ascending scale of inletdepeadejice, in which plants 

 should minister to animals, and animals to man,* may be fairly assumed. 

 But this is only to remove the question one stage back. Whence did 

 this universal Nature (j; toO oXov (pvaa) derive its principle of harmony 

 and excellence.? Was it a something self-existing, or something, Hike 

 the orderly discipline of an army, which, though apparently inherent, 



' D. G. iv. 10, 10. 2 Cf. ii. I, note 4. 



* Met. xi. (xii.) 10, 2. The passage is worth quoting, if only for the "noblesse oblige" 

 simile. '* The universe is not so constituted that there is no interdependence between 

 one thing and another. Such relation does in truth exist. For all things have been 

 ordered together as part of one whole ; and all things, the fowls of the air, the fishes of 

 the sea, and the plants of the earth, have been in some wise brought into harmony with 

 each other, though not all in equal degree. It is as in a household ; where the masters 

 are by no means at liberty to act by chance, but in all or most of their doings are guided 

 by fixed rules ; while the slaves and animals do some little for the common weal, but for 

 the most part act by chance, and follow the dictates of their individual natures." 



*Polit. i. 8, II. 



