Rabbah bar Nachmani ran one of the great academies of Babylonia, and twice a year — in the month before Passover and the month before the Feast of Tabernacles — thousands of Jews traveled to hear him teach. Twelve thousand students, the tradition says. The king's tax collectors discovered that when they came to collect the annual poll-tax on these twelve thousand men, the villages where they lived were empty. Everyone was at Rabbah's academy.
The king was not pleased. A royal messenger was dispatched to arrest the rabbi.
Rabbah fled. He went to Pumbeditha, then to Akra, then to Agmi, then to Sichin, then to Zeripha, then to Ein d'Maya, and finally back to Pumbeditha. And by one of those twists that only a talmudic tale allows, the royal messenger and the fugitive rabbi ended up at the same inn, on the same night, without knowing who the other was.
The innkeeper set two cups of wine before the messenger. He drank both. When the table was taken away, his face — suddenly — twisted around to the back of his neck.
This was the work of the shedim, the rabbis explained. Pairs of things (zugot) are dangerous; drinking an even number of cups opens a door for demonic mischief (Pesachim 110a).
The terrified innkeeper went to the hidden rabbi for advice. Rabbah told him to have the table placed before the messenger again, and to prepare an odd number of cups. The balance would be restored.
The king's agent was healed, the rabbi escaped, and the academy resumed (Bava Metzia 86a). Tradition turns tax evasion into a parable: the study of Torah runs on a different calendar than the empire, and heaven defends its scholars with strange tools.