196 THE METAPHYSICS OF EVOLUTION. 



Now the metaphysical Implications of the potent- 

 ial and the actual, z.^., of the theory of Evolution in 

 its only tenable form, were fully worked out by 

 Aristotle more than 2,000 years ago. Aristotle's doc- 

 trine of potentiality and actuality (Svva^ig and evepyeia) 

 is the most complete form of evolutionism conceiv- 

 able. It admits of no differences in kind anywhere 

 in the universe. From the lowest form of matter 

 to the highest form of mind, the lower is the potent- 

 iality of which the higher is the actuality or real- 

 ization. And so we ascend by insensible gradations 

 from the first matter (prothyle), which is merely 

 potential and never actual {cf. § 13), to the divine 

 being which has completely realized all its potenti- 

 alities, i.e., is all it can possibly be. 



It is true, however, that Aristotle does not con- 

 ceive this process from the potential to the actual 

 to be one in Time, as the historical theories of 

 Evqlution are wont to do, but supposes the different 

 degrees of perfection to coexist in Space rather than 

 to $uc,ceed one another in Time. For he regards the 

 world as eternal, and rejects the supposition of a 

 secular progress in things. 



But it is remarkable that he rejects it merely on 

 the ground of lack of evidence. It would be 

 absurd, he says,^ on account of slight and brief 

 changes, like the growth of the Nile delta, to sup- 

 pose a general cosmic motion (kiv6iu to irav). 



Thus, for lack of the requisite scientific illustration, 

 the true theory of Evolution had to remain still-born 

 for 2,000 years, until the progress of physical science 

 could ratify the results Aristotle had anticipated ! 

 But as soon as the scientific evidence was forthcom- 

 ing, it was found necessary to revive Aristotl 

 ^ Meteorol. I. 14. 



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