What is "kathekon"

Kathēkon (plural: kathēkonta ) is a Greek concept, forged by the founder of Stoicism, Zeno of Citium. It may be translated as "appropriate behaviour", "befitting actions," or "convenient action for nature", or also "proper function." Kathekon has been translated in Latin by Cicero as officium, and by Seneca as convenentia. Kathēkonta are contrasted, in Stoic moral, with katorthōma (κατόρθωμα; plural: katorthōmata), roughly "perfect action." According to Stoic philosophy, man (and all living beings) must act in accordance with Nature, which is the primary sense of kathēkon.