INTRODUCTION. IX 



is in reality dependent on a general in the background ? Aristotle 

 himself asks ^ the question, but gives no answer. This much, however, 

 seems clear. The general, if general there. were, could not be the 

 extra-cosmic God whose existence is postulated in the Metaphysics, 

 the " Unmoved that causes motion as an object of desire ; " for his 

 life was an undisturbed ecstacy of self-contemplation. But whether 

 there were other divine essences of less serene attributes, answering to 

 the inferior gods who in the Timaeus are interposed between the 

 Demiurgus and mortal beings, of whose intelligent activity Nature was 

 but the expression, is a question which, whatever surmise we may form 

 from a few stray and hazy passages, admits of no definite solution. 

 In the biological treatises there is no reference whatsoever to the re- 

 lation in which, if in any. Nature stands to God. In these Aristotle 

 limits himself to the teachings, or supposed teachings, of the senses. 

 These revealed to him the phenomena of animal life, and he wrote of 

 them. They showed him also, or seemed to show him, as plainly as 

 his eyes showed him the existence of colour, that these phenomena 

 were not explicable by reference to the ordinary properties of inanimate 

 matter, but implied the action of some other and co-ordinating force. 

 They told him also something of the conditions and limitations under 

 which this force acted, and with these, also, he deals. But they told 

 him nothing of the origin of this force, and, whatever may have been 

 his ideas as a metaphysician, as a biologist he was silent. 



Having in the first book of this treatise laid down his general position, 

 Aristotle proceeds in the rest of the work to deal with the application 

 of his views to particulars. With this purpose he takes the various 

 parts of the body, both tissues and organs, one after the other, into* 

 consideration, and praises to examine in e^i case how far the struc- j 

 ture is the outcome oF^gceaai^, how far ^-^PPt^iF"^ ^'^^Ifir"- Such, I 

 say, is his profession. His actual practice is merely to see if it be 

 possible to find any ^use. real or imaginary, for a given structure, and 

 if such can be devised, at once to claim that structure, without further 

 argument, for design. Seeing how fertile was his fancy in generating 

 final causes, it will be readily understood how scanty a margin remained 

 after this process as the share of necessity. One set of structures indeed 

 there was which seems to have caused him much difficulty. These were 

 the organs which we now-a-days know as rudimentary parts. The inutility 

 of these was too striking to escape notice, and seemed to exclude them 

 from the predesigned plan of Nature, that " makes nothing without a 

 purpose." Were they then the offspring of mere necessity } To this 

 question Aristotle never gives a definite answer. He speaks in many 



1 Met. xi. (xii.) lo, I. 



