INTRODUCTION 



That the De incessu animalium is a genuine work of 

 Aristotle himself has never been disputed. The De 

 motu animalium has been regarded by many critics as 

 a spurious work, though recent opinion has favoured 

 its genuineness. Brandis, Rose and Zeller all con- 

 demn it, but its Aristotelian authorship has been up- 

 held by Werner Jaeger {Hermes, xlviii. pp. 31 ff.), who 

 makes out a very strong case in its favour, and by the 

 Oxford translator, Mr. A. S. L. Farquharson. Those 

 who deny its authenticity rely mainly on the supposi- 

 tion that there is a reference in 703 a 10-1 1 to the De 

 spiritu. This treatise is generally admitted to be un- 

 Aristotelian, but the reference, as Mr. Farquharson 

 has pointed out, might relate equally well to numerous 

 other passages in the Aristotelian corpus ; Michael 

 Ephesius refers it to a treatise Tlepl Tpo(f>yj<i, not 

 otherwise known. In style, vocabulary and syntax 

 the De motu animalium is entirely Aristotelian, and its 

 doctrine corresponds with that set forth in Aristotle's 

 genuine works. 



Each treatise has its proper place in the scheme of 

 Aristotle's biological works. Both are theoretical, 

 the De incessu animalium, like the De partihus ani- 

 malium, dealing with the material side of living things, 

 and the De motu animalium, like the De generatione 

 animalium, dealing with their consequential pro- 

 perties. 



436 



