Callippus

At the same time, he must have learnt much from other contemporaries at Athens, especially from astronomers such as Eudoxus and Callippus, and from orators such as Isocrates and Demosthenes.

Plato and Speusippus in the Ethics, Eudoxus and Callippus in the Metaphysics, he was writing these passages after the deaths of these persons; but he might have been also writing the Ethics and the Metaphysics both beforehand and afterwards.

Similarly in astronomy, Aristotle used the assistance of Eudoxus and Callippus.

He had, however, scarcely made himself master of Sicily when the people began to express their discontent with his tyrannical conduct, and he was assassinated by Callippus, an Athenian who had accompanied him in his expedition.

A conspiracy, headed by Callippus, put an end to his reign.