And is that sacrifice an effective defence? Minus our freedom, we may find ourselves no safer; indeed we may be double-plus unfree, having handed the keys to those who promised to be our defenders but who have become, perforce, our jailers. A prison might be defined as any place you’ve been put into against your will and can’t get out of, and where you are entirely at the mercy of the authorities, whoever they may be. Are we turning our entire society into a prison? If so, who are the inmates and who are the guards? And who decides?

WE HUMAN BEINGS have been exploring the border between freedom and unfreedom for a very long time. Long ago, the alternative to freedom was not imprisonment but death. In the millennia we spent as hunter-gatherers, we had neither passwords nor prisons. Everyone in your small group knew and accepted you, though strangers were suspect. No one got put in jail, because there were no buildings to serve that purpose. If a person became a threat to the group – for instance, if he became psychotic and expressed a desire to eat people – it would be the duty of the group to kill him, whereas nowadays it would be the duty of the group to lock him up, in order to keep others from harm. A justice system with an incarceration option depends on permanent architecture: you can’t throw someone into a dungeon unless you have one.

After the advent of agriculture, the alternative to freedom became not death but slavery. It was now more desirable to enslave the threats to your group than to kill them. That way, they could be set to work tilling your soil, thus creating a surplus for you and making you rich. Sampson isn’t tossed off a cliff, as were the captured male Trojans in the Homeric epics. Instead he is blinded and set to work grinding grain like a donkey.

Of course, once the profitability of slaves had been recognised, the rule of supply and demand created a thriving market for slaves. You could find yourself enslaved not only by being on the losing end of a war, but by being in the wrong place at the wrong time: in the path of a slave-raiding party, for instance.