what is the Two-Post rule?

Name: Jones McCaw

Age: 116

Gender: Male

Species: Birdman

Appearence: Half bird, half man. he has a head that looks a lot like a crow. He stands upright, with black feathers. He wears a monocle and a vest and he talks in a british accent.

Personality: Soft spoken and gentle, he tries to help the people around him. He's not much help though, due to being a coward.

Bio: Born to a rich family on the planet Gary, Jones was destined to be a banker. He finished 50 short years of school and went off to join the buisness. Unfortunately for Jones, he didn't realise how cutthroat bankers had to be and he soon left.
While looking for work, a friend told him he should be a doctor. Jones is a coward, though and turned the offer down immdiatley. 
The planet is low on doctors, so gangs of doctors try to push people into the job. One day while coming home from his search, Jones was ambushed. He was brought underground and forced to study the art of operations, when one day a portal appeared...