In 302, the Roman emperor Diocletian commanded "there should be cheapness," declaring, "Unprincipled greed appears wherever our armies ... march. ... Our law shall fix a measure and a limit to this greed." The predictable result of Diocletian's food price controls were black markets, hunger and food confiscation by his soldiers. Despite the disastrous history of price controls, politicians never manage to resist tampering with prices -- that's not a flattering observation of their learning abilities.