Aristotle 41 



vegetative soul. ' It is then in virtue of this principle that all 

 living things live, whether animals or plants. But it is sensation 

 which primarily constitutes the animal. For, provided they 

 have sensation, even those creatures that are devoid of move- 

 ment and do not change their place are called animals. . . . 

 As the nutritive faculty may exist without touch or any form 

 of sensation, so also touch may exist apart from other senses.' l 

 Apart from these two lower forms of soul, the vegetative 

 or nutritive and reproductive and the animal or sensitive, 

 stands the rational or intellectual soul peculiar to man, a 

 form of soul with which we shall here hardly concern our- 

 selves. 2 



The possession of one or more of the three types of soul, 

 vegetative, sensitive, and rational, provides in itself a basis for 

 an elementary form of arrangement of living things in an 

 ascending scale. We have already seen that Aristotle certainly 

 describes something resembling a ' Scala Naturae ' and that 

 such a scheme can easily be drawn up from passages in his works. 

 It may, however, be doubted whether his phraseology is capable 

 of extension so as to include a true classification of animals in 

 any modern sense. It is true that he repeatedly divides 

 animals into classes, Sanguineous and Nonsangyineous, Oviparous 

 and Viviparous, Terrestrial and Aquatic, &c., but his divisions 

 are for the most part simply dichotomic. He certainly defines 

 a few groups of animals as the Lophura (Equidae), the Cete 

 (Cetaced), and the Selache (Elasmobranchiae together with the 

 Lopbiidae) in a way that fairly corresponds to similar groups 

 in later systems. In most cases, however, his definitions are not 

 exact enough for modern needs, for the same animal may fall 

 into more than one of his classes and widely different animals 



1 De anima, if. 2, ii ; 41 3 a 22. 



The question of Aristotle's meaning in connexion with this topic, of 

 primary importance for all thought, has a vast literature. An authoritative 

 work is R. D. Hicks, Aristotle, De anima^ Cambridge, 1907. 



