Here's another one for you: liturgy.
Liturgy to us means public worship. Liturgy to the ancient Greeks meant a public service, to do something or make a donation, for the public good.
The first liturgy probably happened when a few wealthy men donated to the state out of the goodness of their hearts, but by classical times the liturgy had become a formal institution. Every year the archons--those are the city magistrates--would decide what liturgies needed to be performed--in effect, they declared a public works program--and then they waited for volunteers to take on the jobs. In return for performing a liturgy, the volunteer would receive great honour and kudos.
There were certain standard liturgies, and some were more popular than others.
The wealthy and powerful probably queued up for the privilege of being a choregos. That meant funding and putting on a play at one of the great arts festivals. All the famous Greek tragedies were funded as a liturgy. The honour of being choregos was so great that I wouldn't be surprised if sometimes money changed hands, or unscrupulous deals were done to win the job.
Pericles got a choregos gig very early in his career. He hired Aeschylus, the inventor of tragedy, to write and put on a play called The Persians. Pericles and Aeschylus between them probably designed the play to score a political point about the superiority of the Greeks. Interestingly, The Persians is the oldest play to survive to modern times, so in a very real sense it's the beginning of drama.
Likewise, sports fanatics very happily volunteered to manage the athletics teams. That liturgy was called the gymnasiarchy and was done at the gymnasium.
The liturgy called the trierarchy was of the greatest importance, because it meant to maintain a trireme in the Athenian Navy. The wealthy man who took this on became the ship's captain for the year, and was entitled to call himself Trierarch. Who wouldn't want to be captain of Salaminia or Paralos, the two most famous warships of the ancient world? The modern equivalent would be if, say, Bill Gates paid for a nuclear powered aircraft carrier out of his own pocket, and then became it's captain in return.
The liturgy of the trierarch gets a mention in passing in my second book. Nico is being wafted to a vital mission aboard Salaminia, and he says this to the captain:
"Have you been a sailor all your life, sir?"But not everyone wanted to do a liturgy. These things cost a fortune and not everyone is public-spirited. After the popular liturgies were taken there'd always be leftovers. What happened then was, the archons assigned them to the richest men who hadn't volunteered.
The Trierarch laughed. "Me? A sailor? Poseidon protect me, no."
"Then, why are you...that is, what–"
"What am I doing here? I paid for the ship, young man; every board, every rope, every fitting, every plank. It's my gift to the state, because I am wealthy, part of my obligations under the liturgy, the convention that says wealthy men must spend their wealth to the benefit of the state. So I get to call myself Trierarch, and strut about the deck as if I know what I'm doing. The truth is, the best sailor on this ship is him," the Trierarch pointed to the helmsman; a grizzled, burnt, unsmiling man. "I'm the one who gets the glory of command; he's the one who gives the orders when it really matters."
The Trierarch wandered off to do some more strutting and glorying.
Usually the victim just sighed and paid the money. To this extent, the liturgy was like a wealth tax.
But the law gave him another option. The victim could name another man wealthier than himself to do the job, someone who didn't already have a liturgy assigned.
A man who's been assigned a liturgy--let's call him Ariston--could point out a fellow citizen--let's call him Braxas--and say, "Braxas over there has more money than me, so he should fund the public feasts."
If Braxas really did have more money, then the law required him to take on the liturgy, and Ariston didn't have to pay a thing. So the liturgy was like a wealth tax with some elements of a hot potato.
But if Braxas refused, and said Ariston was the richer, then Ariston could either give up and pay the liturgy, or else he could invoke the rule of antidosis. Antidosis means "to give in exchange". This rule said that if Ariston still maintained that Braxas had more money, and if Braxas insisted that he didn't, then the two men were required by law to swap everything they owned. Every. Single. Thing. They. Owned.
Ariston was then required to pay for the liturgy, but since he now, by his own insistence, has more money than he did before, he's hardly in a position to complain.
Antidosis meant that Ariston would have to be dead sure of his facts, or he'd end up with less wealth and still have to pay the liturgy anyway. Conversely, Braxas would have to be honest about his holdings, or he might avoid the liturgy at the cost of losing even more wealth.
I imagine that when antidosis got invoked, it must have been a tense situation, and caused both parties to eye the other's property in minute detail. The antidosis rule effectively outsourced to private citizens the much hated problem of tax auditing, in such a way that you knew they'd do it with great accuracy.
You can imagine how much fun everyone else would have had watching one of these cases in process. We only know of antidosis being invoked a few times, and every time the man on the Braxas side backed down. But there surely must have been more cases than we know of.
I'd love to see the liturgy and the rule of antidosis in use today. It's a tax system that doesn't cost the state a cent (or a drachma) to administer, because the citizens themselves do all the enforcement. Even amongst all the genius ideas that the Athenians came up with, this surely must be one of their greatest.