"No," he said slowly, "you don't start it if you can't finish it." Meaning to do a thing had nothing to do with anything. All that mattered was that you succeeded. And if you didn't, you deserved to get caught. That was what Pollux had learned, the lessons of his youth and his early adulthood stood out to him as fresh as newly fallen snow.
So did the brutality of those teaching methods. It had been necessary to learn though. And he was a better wizard for it. Though it seemed Sirius missed that much of his education, given his lack of control over his own emotions. The outburst made Pollux uncomfortable, nervous and a little trigger happy. But he contained it to the best of his ability and tried to steer away from the danger.
Then Sirius was standing and half naked and it scandalized Pollux for half a heartbeat. He looked away. "Put your clothes back on," he said.