Chrysippus of Soli (kraɪˈsɪpəs,_krɪ-; Χρύσιππος ὁ Σολεύς, Chrysippos ho Soleus; 279 – 206 BC) was a Greco-Phoenician Stoic philosopher. He was a native of Soli, Cilicia, but moved to Athens as a young man, where he became a pupil of the Stoic philosopher Cleanthes. When Cleanthes died, around 230 BC, Chrysippus became the third head of the Stoic school. A prolific writer, Chrysippus expanded the fundamental doctrines of Cleanthes' mentor Zeno of Citium, the founder and first head of the school, which earned him the title of the Second Founder of Stoicism.
Chrysippus excelled in logic, the theory of knowledge, ethics, and physics. He created an original system of propositional logic in order to better understand the workings of the universe and role of humanity within it. He adhered to a deterministic view of fate, but nevertheless sought a role for personal freedom in thought and action. Ethics, he thought, depended on understanding the nature of the universe, and he taught a therapy of extirpating the unruly passions which depress and crush the soul. He initiated the success of Stoicism as one of the most influential philosophical movements for centuries in the Greek and Roman world.
Of his several written works, none have survived except as fragments. Recently, segments of some of his works were discovered among the Herculaneum papyri.
Of Phoenician descent, Chrysippus was the son of Apollonius of Tarsus, and he was born at Soli, Cilicia. He was slight in stature, and is reputed to have trained as a long-distance runner. While still young, he lost his substantial inherited property when it was confiscated to the king's treasury. Chrysippus moved to Athens, where he became the disciple of Cleanthes, who was then the head (scholarch) of the Stoic school. He is believed to have attended the courses of Arcesilaus and his successor Lacydes, in the Platonic Academy.
Chrysippus threw himself eagerly into the study of the Stoic system. His reputation for learning among his contemporaries was considerable.