It is after four on Wednesday afternoon, and it’s a week since he’s been back. His absence has not been remarked upon, and he sees no value in mentioning it while no one else does. Now he teaches as he did two years ago. Tomorrow a version of himself will be by the corner, and he will have to remember to avoid him.
Travelling in time is like travelling in India; the truly embarrassing things lie repressed in your mind, waiting to haunt the future. In his case, the memories may be more vivid than of most travellers. Tomorrow he will see himself as he was a year ago, uncool, fumbling around in a jumper and uneasy hair. He will stare from his window and he will blush, but he will not yell out at himself because the universe will explode. He cannot yell because he has not yelled, his future is dictated by his past and his past happens in the future. He thinks he might have saved the world tomorrow, but the details are hazy now.
Today in class they did the planets, learning the sizes and distances by rote. He’s been to them all except Neptune, and he thinks the pupils notice the irritation in his voice when he mentions it. They were in the kind of mood they always were, but space is fascinating to those who’ve been kept in a tiny part of it, and their madness was held by longing of a kind. They talk about Johnson and the moon and ask him how long it’ll be, and they look out of the window because it’s visible, now, hanging in the sky on a Wednesday afternoon. He’s been to the moon before like no other man in the world, but he did it far in the future, when it was covered in suburbs and factories for making candy floss. He remembers how many people were there, how mundane it all seemed. He might have saved the world again, that time.
It's 1965, the moon is bare. He is teaching. He’s the only man on Earth who’s been up there yet he knows he’ll never be the first; you can't change history, not even one line. And yet that thought doesn’t seem to have stopped her. In the room down the corridor she's wilder than ever before, talking about the Aztecs and the Romans as though they were real, not the half-imagined characters of facts and dates that everyone really knows and believes in. But then perhaps that sort of thing is harmless in her profession; you can’t change history. He knows only too well that he could change science. In his head are formulae for faster than light travel, the means to build an irrigation system out of sound and the knowledge that he cannot ever tell anyone any of it. They’ll appreciate his lessons, though, these children, he’s read their yearbooks in the future. He’ll teach them and they’ll leave and forget, they'll learn and they'll thank him and they'll die; you can't change history. These days he has the feeling it changes enough on its own. Outside it is four and it is Wednesday, the flags are half-masted and the Queen is dead, as she wasn’t when he left and as she won’t be tomorrow…
In his room at four he keeps on marking, in ink that he knows can only fade with time.