HERE is what sometimes happened to me: after spending the first part of the night at my desk—that part when night trudges heavily uphill—I would emerge from the trance of my task at the exact moment when night had reached the summit and was teetering on that crest, ready to roll down into the haze of dawn; I would get up from my chair, feeling chilly and utterly spent, turn on the light in my bedroom, and suddenly see myself in the looking glass. Then it would go like this: during the time I had been deep at work, I had grown disacquainted with myself, a sensation akin to what one may experience when meeting a close friend after years of separation: for a few empty, lucid, but numb moments you see him in an entirely different light even though you realize that the frost of this mysterious anesthesia will presently wear off, and the person you are looking at will revive, glow with warmth, resume his old place, becoming again so familiar that no effort of the will could possibly make you recapture that fleeting sensation of estrangedness. Precisely thus I now stood considering my own reflection in the glass and failing to recognize it as mine. And the more keenly I examined my face—those unblinking alien eyes, that sheen of tiny hairs along the jaw, that shade along the nose—and the more insistently I told myself “This is I, this is So-and-so,” the less clear it became why this should be “I,” the harder I found it to make the face in the mirror merge with that “I” whose identity I failed to grasp. When I spoke of my odd sensations, people justly observed that the path I had taken led to the madhouse. In point of fact, once or twice, late at night, I peered so lengthily at my reflection that a creepy feeling came over me and I put out the light in a hurry. Yet next morning, while shaving, it would never occur to me to question the reality of my image.