“If what philosophers say of the kinship of God and Men be true, what remains for men to do but as Socrates did: never, when asked one’s country, to answer, 'I am an Athenian or a Corinthian,' but 'I am a citizen of the world.”

Compare doctrine of fidelity to Athenian law in Plato's Crito.
Plutarch

Diogenes, 6.
The Lives and Opinions of Eminent Philosophers (c. 200 A.D.), Book 6: The Cynics

Source: The Green Mile

Of Banishment
Bartlett's Familiar Quotations, 10th ed. (1919)
Variant: Socrates said he was not an Athenian or a Greek, but a citizen of the world.

As quoted in Writers on Writing‎ (1986) by Jon Winokur.
Variant: If you ask me what I came into this life to do, I will tell you: I came to live out loud.

1840s, Heroes and Hero-Worship (1840), The Hero as Prophet

29b [alternate translation]
Plato, Apology

Source: Uncle Tungsten (2001), p. 182