ARISTOTLE AS A BIOLOGIST 27 



mutual exclusiveness, but just as we may discern a triangle 

 within a square, so is each lower grade of 'tyvyji implicit 

 in the higher. And as the higher organisms retain the 

 main physiological faculties of the lower, so do they retain 

 such psychological qualities as these possess : and 

 gradually (more and more as we ascend the ladder) do we 

 find adumbrations of the psychical qualities that will be 

 perfected in the higher forms. Among the higher 

 animals, at least, a comparative psychology may be 

 developed ; for just as their bodily organs are akin to one 

 another's and to man's, so also have we in animals an 

 inchoate intelligence, wherein we may study, in one or 

 another, the psychology of such things as fear, anger, 

 courage, and at length of something which we may 

 call sagacity, which stands not far from reason. And, 

 last of all, we have a psychology of childhood, wherein 

 we study in the child, at first little different from the 

 animal, the growing seeds of the mind of man. 



But observe before we leave this subject that, though 

 Aristotle follows the comparative method, and ends by 

 tracing in the lower forms the phenomena incipient in the 

 higher, he does not adopt the method so familiar to us all, 

 and on which Spencer insisted, of first dealing with the 

 lowest, and of studying in successive chronological order 

 the succession of higher forms. The historical method^ 

 the realistic method of the nineteenth century, the 

 method to which we so insistently cling, is not the only 

 one. Indeed, even in modern biology, if we compare 

 (for instance) the embryology of to-day with that of thirty 

 years ago, we shall see that the pure historical method 

 is relaxing something of its fascination and its hold. 

 Rather has Aristotle continually in mind the highest of 

 organisms, in the light of whose integral and constituent 

 phenomena must the less perfect be understood. So was 



