“Asked where he came from, he said, "I am a citizen of the world."”

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.

2013, Commencement Address at Ohio State University (May 2013)
Context: I don’t pretend to have all the answers. And I’m not going to offer some grand theory – not when it’s a beautiful day and you’ve got some celebrating to do. I’m not going to get partisan, either, because that’s not what citizenship is about. In fact, I am asking the same thing of you that President Bush did when he spoke at this commencement in 2002: “America needs more than taxpayers, spectators, and occasional voters,” he said. “America needs full-time citizens.”
And as graduates from a university whose motto is “Education for Citizenship,” that’s what your country expects of you. So briefly, I will ask you for two things: to participate, and to persevere.
After all, your democracy does not function without your active participation. At a bare minimum, that means voting, eagerly and often. It means knowing who’s been elected to make decisions on your behalf, what they believe in, and whether or not they deliver. If they don’t represent you the way you want, or conduct themselves the way you expect – if they put special interests above your own – you’ve got to let them know that’s not okay. And if they let you down, there’s a built-in day in November where you can really let them know that’s not okay.

Source: The Truth

Sons and Lovers - Edited out of the 1913 edition, restored in 1992

As translated in The Zen Poetry of Dōgen : Verses from the Mountain of Eternal Peace (1997) by Steven Heine, p. 61

Source: Liberalism (1911), Chapter V, Gladstone And Mill, p. 56 .

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.

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

15
Golden Sayings of Epictetus