Zeno of Citium (c. 336 – 265 BCE) was a Greek philosopher and the founder of the Stoic School of philosophy, born in the Phonecian-Greek city of Citium on Cyprus in the same year that Alexander the Great ascended to the throne of Macedonia. His father was a merchant who travelled often to Athens, and Zeno naturally took up his father’s profession. It is unclear whether Zeno studied philosophy in his youth, but around the age of 22, while stranded in Athens after a shipwreck, he picked up a copy of Xenophon’s Memorabilia and was so impressed by the figure of Socrates that he abandoned his former life and made the study of philosophy his only interest. Zeno studied under Crates (who was a student of Antisthenes, one of Socrates' students and the founder of the Cynic School) and then under Stilpo the Megarian and then became the pupil of Polemo. From each of these men he learned some different aspect and nuance of the life of a philosopher (from Stilpo, for example, it is said he learned that the greatest fault in life lay in saying 'yes’ too quickly to any request and one should avoid doing so in order to live a tranquil life). After many years of study, Zeno set up his own school and began to teach on the porches (the stoa) of the arcade in the market place in Athens, and thus his school took the name of the place of learning: Stoic. It is alleged that Zeno said, “I made a prosperous voyage when I was shipwrecked” and that would certainly seem to be so as he was praised highly by the Athenians for his temperance, his consistency in living what he taught, and his good effect on the youth of the city. Zeno never seems to have been one to hold his tongue, however, when he saw what he perceived as foolishness in the youths and many of his remarks sound similar in tone to the scathing criticisms of contemporaries associated with the 'mad' philosopher Diogenes of Sinope. When he studied under Crates, Zeno wrote his Republic which is quite a different vision than the ideal city state as imagined by Plato in his work of the same name. Zeno’s Republic is a utopia whose citizens claimed the universe as their home and where everyone lived in accordance with natural laws and rational understanding. There were no laws necessary because there was no crime and, because everyone’s needs were taken care of in the same way that animals are in nature, there was no greed, nor covetousness nor hatred of any kind. Love governed all things and everyone living in this cosmopolis understood they had what they needed and wanted for nothing more. Zeno died in 265 BCE, apparently from suicide, after he tripped coming out of the school and broke his toe. Lying on the ground, he quoted a line from the Niobe of Timotheus, “I come of my own accord; why call me thus?” and then, interpreting the accident as a sign he should depart, strangled himself.

Cleanthes (c. 330 BC – c. 230 BC), of Assos, was a Greek Stoic philosopher and the successor to Zeno as the second head (scholarch) of the Stoic school in Athens. Originally a boxer, he came to Athens where he took up philosophy, listening to Zeno's lectures. He supported himself by working as water-carrier at night. After the death of Zeno, c. 262 BC, he became the head of the school, a post he held for the next 32 years. Cleanthes successfully preserved and developed Zeno's doctrines. He originated new ideas in Stoic physics, and developed Stoicism in accordance with the principles of materialism and pantheism. Among the fragments of Cleanthes' writings which have come down to us, the largest is a Hymn to Zeus. His pupil was Chrysippus who became one of the most important Stoic thinkers." — Wikipedia