Followers of Stoicism offer for consideration various metaphysical systems, united chiefly by their ethical implications. All variants on the pantheistic theme that the world constitutes a single, organically unified and benevolent whole, in which apparent evil results only from our limited view. Their philosophy had at its core the beliefs that virtue is based on: Knowledge, Reason and Harmony.

The changes of circumstances were viewed with evenness of mind: pleasure, pain, and even death were irrelevant to true happiness. In time, the idea that only the accomplished wise man (the philosopher) could attain virtue was challenged, and Stoicism became more relevant to the reality of politics and statesmen.

The Stoic belief in the brotherhood of man helped philosophy to make a real impact in later Republican Rome, upon such men as the young Cato (whose suicide brought him a martyr's fame), Brutus, and Cicero. Its disciples included Seneca, tutor and adviser to Nero and the emperor Marcus Aurelius.