Socrates died in 399 BC. 46 years later Plato dies in 347 BC. Aristotle lives 20 years after Plato’s death and dies in 322 BC.
Those are the three pillars.
If you strip Stoicism of its paradoxes what is left is simply the philosophy of Socrates, Plato and Aristotle.
Eugen Weber provides a solid background of Stoicism until that time the part it played in the formation of Christianity.
Zeno is often regarded as the founder of Stoicism. But alas, that is wholly not true. Zeno was operating much like a news anchor who take all news reports from news reporters and gives them voice. The news reporters are the originators of the news, they risk their lives and do the hard work.
The lifespan of Zeno was from B.C. 347 to 275. He did not begin teaching till 315, at the mature age of forty. Which means he started teaching seven years after the death of Aristotle in 322.
As, I already said, Zeno did not add much to the body of Philosophy, he only did a great work in popularising it and bringing it to bear upon life.
Zeno’s wealthy merchant father bought him the writings of the Socratic philosophers at a very young age.
Zeno regarded philosophy as the art of life. And according to him the art of life is to ‘to live consistently with nature.’ This view was to be taken and elaborated further by Jean Jacques Rousseau in the 18th century when he talked about the return to nature.
It is assumed by the Stoicism that the ways of nature were ‘the ways of pleasantness,’ and that ‘all her paths’ were ‘peace.’
Two things here; Man’s life is based on reason because he has a mind. And the perfection of reason is virtue, or to put it the other way round, when a person reasons well he is regarded as being virtuous. Virtue is when you are able to reason well. To reason well is to be in accordance with nature.
The things that are in accordance with nature are such as health, strength, good bodily condition, soundness of all the senses, beauty, swiftness—in short all the qualities that went to make up richness of physical life and that contributed to the vital harmony. These were called the first things in accordance with nature. Their opposites were all contrary to nature, such as sickness, weakness, mutilation.
The character of stoicism is a person who is cosmopolitan. Cosmopolitanism is a word which has contracted rather than expanded in meaning with the advance of time. We mean by it freedom from the shackles of nationality. The Stoics meant this and more.
Epictetus lived and taught at Rome until AD. 90 when the philosophers were expelled by Domitian. He left Rome and went to Nicopolis in Epirus, where he spent the rest of his life. Epictetus wrote nothing himself, but his Dissertations, as preserved by Arrian, from which the Encheiridion is excerpted, contain the most pleasing presentation that we have of the moral philosophy of the Stoics.
Concerning philosophy in general, the doctrine of the Stoics was, that wisdom consists in the knowledge of things divine and human; that philosophy is such an exercise of the mind as produces wisdom; that in this exercise consists the nature of virtue; and consequently, that virtue is a term of extensive meaning, comprehending the right employment of the mind in reasoning, in the study of nature, and in morals.
Zeno lived to the extreme age of ninety-eight. He preserved his health by his great abstemiousness, his diet consisting of figs, bread, and honey.
Zeno was well known far and wide, and enjoyed a celebrity life.
