24 FATHERS OF BIOLOGY. 



sect received the name of the Peripatetics. The dis- 

 courses were of two kinds the esoteric, or abstruse, and 

 the exoteric, or familiar ; the former being delivered to 

 the more advanced pupils only. During the greater part 

 of this time Aristotle kept up correspondence with 

 Alexander, who is said l to have placed at his disposal 

 thousands of men, who were busily employed in collect- 

 ing objects and in making observations for the com- 

 pletion of the philosopher's zoological researches. 

 Alexander is, moreover, said to have given the philo- 

 sopher eight hundred talents for the same purpose. 



In spite of these marks of friendship and respect, 

 Alexander, who was fast becoming intoxicated with 

 success, and corrupted by Asiatic influences, gradually 

 cooled in his attachment towards Aristotle. This may 

 have been hastened by several causes, and among others 

 by the freedom of speech and republican opinions of 

 Callisthenes, a kinsman and disciple of Aristotle, who 

 had been, by the latter's influence, appointed to attend 

 on Alexander. Callisthenes proved so unpopular, that 

 the king seems to have availed himself readily of the 

 first plausible pretext for putting him to death, and to 

 have threatened his former friend and teacher with a 

 similar punishment. The latter, for his part, probably 

 had a deep feeling of resentment towards the destroyer 

 of his kinsman. 



1 Pliny, " Natural History," viii. c. 16. 



