I am a second-year graduate student, and my advisor is an old professor in his fifties. He's quite kind, just a bit untidy.

Once, he asked me to go to his office to revise a paper, and when I arrived, the door was wide open.
I sat down and said, "Professor, should we close the door? The corridor is a bit noisy."
He looked up at me and said something that I still remember vividly: "No need to close it. If you don't want to close it, I don't want to close it either."
I was stunned for a moment and didn't quite understand at first.