I stared at the words on my computer screen for long enough that the depths and dimensions beyond the edges of my computer screen started to play tricks on my perception—slanting slowly side to side, zooming out and then back in. I leaned back and pushed myself away from the desk, rolling in the wheeled chair. I looked at things to the left and right of the screen—a stack of books, a coffee mug. I stared at them and concentrated until I felt that my perception was back to normal. Then I pulled myself to the desk and started typing again.