A pupil and collaborator of Aristotle’s, and his successor as the head of the Peripatetics. Although he was an influential teacher and an energetic writer, few of his works have survived. His philosophy differed from that of Aristotle mainly in an empiricist direction, and in scepticism concerning the extravagances of Aristotle’s teleological approach to nature, but mainly he pursued Aristotelian science and systematization. His treatise On the Opinions of the Physical Philosophers was the major source of later knowledge of the Presocratics.