from an article on Analysis in Plague Time, in this week's New Yorker, a quote from Freud:

I was sitting alone in the compartment of a sleeping car, when, following a sudden jolt of the train, the door to the adjoining toilet opened and an elderly gentleman in a bathrobe, wearing a bonnet on his head, stepped into my sleeper. Assuming that he had confused the two doors as he was leaving the toilet and had mistakenly entered my compartment, I leapt up to explain the situation, but immediately had to recognize, to my chagrin, that the invader was my own image, reflected in the mirror of the door to the toilet. I still remember that I found the appearnace deeply displeasing.