26 FATHERS OF BIOLOGY. 



soon as the political troubles had abated, but in Sep- 

 tember, 322 B.C., he died at Chalcis. An overwrought 

 mind, coupled with indigestion and weakness of the 

 stomach, from which he had long suffered, was most 

 probably the cause of death. Some of his detractors, 

 however, have asserted that he took poison, and others 

 that he drowned himself in the Euboean Euripus. 



It is not easy to arrive at a just estimate of the cha- 

 racter of Aristotle. By some of his successors he has 

 been reproached with ingratitude to his teacher, Plato ; 

 with servility to Macedonian power, and with love of 

 costly display. How far these two last charges are due 

 to personal slander it is impossible to say. The only 

 ground for the first charge is, that he criticised adversely 

 some of Plato's doctrines. 



The manuscripts of Aristotle's works passed through 

 many vicissitudes. At the death of the philosopher 

 they were bequeathed to Theophrastus, who continued 

 chief of the Peripatetic school for thirty-five years. 

 Theophrastus left them, with his own works, to a philo- 

 sophical friend and pupil, Neleus, who conveyed them 

 from Athens to his residence at Scepsis, in Asia Minor. 

 About thirty or forty years after the death of Theo- 

 phrastus, the kings of Pergamus, to whom the city of 

 Scepsis belonged, began collecting books to form a 

 library on the Alexandrian plan. This led the heirs of 

 Neleus to conceal their literary treasures in a cellar, and 



