Stoicism, the significant philosophical school of the Hellenistic and Roman periods (300 BC – approximately 250 AD), was founded in Athens by Zeno of Citium and had as its center the "Stoa Poikile" where his students attended his lectures and were therefore called "Stoics" or Philosophers of the Stoa.

Key principles of Stoic Philosophy include virtue, apathy-ataraxia, freedom, nature, and sympathy, while today it is used to describe a person who is calm under pressure.
The Stoics, instead of envisioning the ideal society, attempted to deal with the world as it was, seeking self-improvement through the virtues of wisdom, gentleness, justice, and integrity. They believed that with personal improvement and self-control, one would also see those around them improve.

According to the Stoics, human nature is part of the universal nature and must live in harmony with the Universe. Man is akin not only to animals but also to God, possesses a moral sense, and the main goal of his life is to live with virtue to ensure tranquility, serenity, ataraxia, and thus happiness. All other things, pleasant or unpleasant, have no value and are simply "indifferent."

The series "Stoic Philosophers," which includes the ancient text, modern Greek translation, and commentary, consists of 12 volumes. Specifically, it includes:

• Epictetus - Discourses I Complete Works 1
• Epictetus - Discourses II Complete Works 2
• Epictetus - Discourses III Complete Works 3
• Epictetus - Discourses IV Complete Works 4
• Epictetus - Enchiridion, Fragments Complete Works 5
• Marcus Aurelius - Meditations I-VI Complete Works 1
• Marcus Aurelius - Meditations VII-XII Complete Works 2
• Posidonius - Fragments 1 Complete Works 1
• Posidonius - Fragments 2 Complete Works 2
• Posidonius - Fragments 3 Complete Works 3
• Plutarch - Moralia 27
• Plutarch - Moralia 28