Doctor Who: Every Prophecy In The Show - Explained
10. The Prophecy Of The Gods
The Time Lord non-interference policy is something that the Doctor regularly waves two fingers at, even though it's basically a law. It stipulates that Time Lords should only observe the events of the universe - and never interfere with them directly.
The Fourth Doctor brings up the origins of the policy in the serial Underworld, when he encounters a group of Minyans onboard the R1C spacecraft. Early on in Minyan history, they met the Time Lords, who possessed advanced technology that allowed them to travel in space and time. Because of this, the Minyans viewed the Time Lords as gods - so the Time Lords offered to help them in return.
They gave the Minyans better technology, greatly accelerating their development as a civilisation. That might sound good on paper, but tragically, the Minyans couldn't handle this sudden burst of power, and they eventually destroyed themselves.
However, this "Time Lords are gods" standpoint is something that rippled through Minyan society down the centuries, eventually becoming a mythical prophecy that a Minyan slave, Idas, relays to the Fourth Doctor.
"There's a prophecy amongst the slaves that one day gods will come and set us free. Are you a god?"
The serial strongly hints that the "gods" in this prophecy are indeed Time Lords, and when you consider that the Minyans once regarded the Time Lords as this higher, almost religious power, that does make sense.