Claudius flinches, on instinct, then goes very still. (Another instinct -- don't move, don't respond, and perhaps this rage will pass him by.) Deliberately, consciously, he breathes in and lets the breath move through him, reminds himself this man would never strike him, that it's only the sound of flesh being struck taking him somewhere else. From that faraway place, he asks, quiet, "Couldst thou?"