Doctor Blitzmann never questioned his sanity. And even if he had, it wouldn't have been able to answer him with its tongue cut out and lips sewn shut. Its constant complaining was distracting him from his work, and that just wouldn't do.
'Sanity is nothing but a bother,' he once told Ulrich. 'I can get rid of yours easily, if you want. No? It's a simple procedure, really.'