Ariston, the m»h of Miltiades and a native of Chios, who introduced the doctrine of things morally indifferent ; Herillus of Carthage, who affirmed knowledge to be the end ; Dionvsius, who became a renegade to the doctrine of pleasure, for owing to the severity of his ophthalmia he had no longer the nerve to call pain a thing indifferent : his native place was Heraclea ; Sphaerus of Bosporus ; Cleanthes, son of Phanias, of Assos, his successor in the school him Zeno used to compare to hard waxen tablets which are difficult to write upon, but retain the characters written upon tjiem. Sphaerus also became the pupil of Cleanthes after Zeno's death, and we shall have occasion to mention him in the Life of Cleanthes. And furthermore the following according to Hippobotus were pupils of Zeno : Philonides of Thebes ; Callippus of Corinth ; Posidonius of Alexandria ; Athenodorus of Soli ; and Zeno of Sidon. a I have decided to give a general account of all the Stoic doctrines in the life of Zeno because he was the founder of the School. I have already given a list of his numerous writings, in which he has spoken as has no other of the Stoics. And his tenets in general are as follows. In accordance with my usual practice a summary statement must suffice. b Philosophic doctrine, say the Stoics, falls into three parts : one physical, another ethical, and the third logical. Zeno of Citium was the first to make this division in his Exposition of Doctrine, and Chrysippus too did so in the first book of his Exposition of Doctrine and the first book of his Physics ; and so