Bristle flinched a little when the master told him that even thoughts weren't safe. Not only his thoughts but now his actions were under control of this master? Even knowing that the master could read these thoughts he still wasn't happy about. Often he didn't gave control of his body but his mind was always a place of refuge. It made sense that they needed to train, if they got hit by something like a fireball they would have to be pretty tough to survive it and from what the master was saying they might have to. Though he was curious to just what extent your physique determined your magical strength. Would the circus's strongman be a good magician on account of just his strength with a little training or would the fortune teller they had be better because of how smart she was? Interesting questions.