Cynicism

Cynicism was the most provocative of the Greek schools, founded in spirit by Antisthenes and embodied by Diogenes of Sinope. Its teaching was stark: virtue is the only good, and it is enough for happiness; everything else — wealth, status, comfort, the opinions of others, the whole apparatus of convention — is worthless and to be cast off.

The Cynic therefore lived 'according to nature' in deliberate poverty and shameless freedom, owning almost nothing, performing in public the self-sufficiency (autarkeia) he preached. The very name, from kynikos, 'dog-like', was a jeer the Cynics wore with pride. Though they founded no formal school and left little doctrine, their ethic of virtue-through-hardship passed directly into Stoicism, which was born from it.