In the ancient world, where life was insecure and refugees and asylum seekers not uncommon, there were no border posts, and free people could mostly come and go at will. But a concept of citizenship, technically differentiating ‘citizen’ from ‘non-citizen’, then emerged among the autonomous communities (‘city-states’: there were hundreds) of the ancient Greeks.

Take 5th century bc Athens. Two Athenian parents were needed to produce citizen offspring, whose status was confirmed and registered by their local deme (a sort of parish). When the males became 18, they were permitted to attend the Assembly which made all the decisions that MPs make on our behalf today, and at 30 they could sit in the courts and stand for office. The fate of Athens was in their hands and no one else’s.

Non-Athenians were, of course, perfectly welcome to visit Athens but, like women and slaves, they had no political rights. But since Athens, with its empire, navy and large population, was a wealthy and intellectually exciting place, traders and many others (Greek and non-Greek) were keen to settle there. These people were recorded in their deme as metoikoi (‘metics’), i.e. immigrants. To stand as surety for them, an Athenian sponsor was needed, with whom they lodged (they could not own property); they paid a monthly tax; they had to serve in the army; those rich enough had to help pay for various festivals (they could also submit plays for performance), but had limited access to religious occasions; they had full access to legal services.

What they did not have was status. Nothing, of course, prevented them forming good working relationships across Athenian society as well as with other metics, but it was citizens’ interests that the Athenian state was set up to protect and advance, as metics openly and sensibly accepted.

Only by vote of the Assembly could a non-Athenian become a citizen. It happened very rarely. Does the relative ease with which anyone today can become a citizen devalue its status? And does it matter?