The great purge haunts him, as it did every timelord. They took them; innocent people, not incredible, not talented. They took the blandest of the lot, and placed them in a chamber. He stood by and watched, powerless to stop it. Kos- The Master's mother was there. She was there and she stared at him with utter, utter desperation. He watched as women and children young children, not even in the academy and men were fired into a blistering hot star.
That drove many insane.
Many were already.