When in doubt...

..., have a man come through the door with a gun
(Raymond Chandler)

He looked as though thinking didn't come easily to him. But it didn't look as though this bothered him a whole lot. Not that I was in much of a position to judge him as I was having something of a hard time thinking of too much myself. Apart from the large, unfriendly-looking knife that he was carrying in an absent-minded way - I found it quite easy to think about that. In particular, I was thinking about precisely how absent-minded he was about the knife. Maybe he had forgotten about it altogether... But, then again, maybe he hadn't. These were the thoughts occupying my mind. They helped to pass the time.