  Diodorus died around 284 BCE at Alexandria in Egypt. His date of birth is unknown. It used to be common to consider him old enough to have influenced Aristotle (died 322 BCE), but there are no strong grounds for this. The dating was based largely on Aristotle’s response in Metaphysics Theta 3 to the modal theory of ‘the Megarics’; but the theory discussed there differs from that of Diodorus, who in any case (see below) should not necessarily be assumed to be a Megaric, however great his debt to the school that went under that name. The best evidence tends rather to make Diodorus an older contemporary of, and a living influence on, the first generation of the Stoic school, which began life ca 300 BCE. Zeno of Citium, the school’s founder, is said to have been a pupil of Diodorus (among others). Among Zeno’s fellow-pupils in Diodorus’s class is reported to have been Philo, himself later a highly original logician in his own right (see the entry on  Dialectical School  in this encyclopedia).