“
Let me guess—you were good at hockey and football when you were at school, but not at tennis.” He laughed at that, eyes crinkling at the corners. “Tennis? At an Inverness grammar school? Soft Southron sport, we’d have called it; game for poofters. But I take your point—no, you’re right, I was fine at the football, but not much at rounders. Why?” “You don’t have any binocular vision,” I said. “Chances are that someone noticed it when you were a child, and made an effort to correct it with prismatic lenses—but it’s likely that it would have been too late by the time you were seven or eight,” I added hastily, seeing his face go blank. “If that’s going to work, it needs to be done very young—before the age of five.” “I don’t … binocular vision? But doesn’t everyone?… I mean, both my eyes do work, don’t they?” He looked mildly bewildered. He looked down into the palm of his hand, closing one eye, then the other, as though some answer might be found among the lines there. “Your eyes are fine,” I assured him. “It’s just that they don’t work together. It’s really a fairly common condition—and many people who have it don’t realize it. It’s just that in some people, for one reason or another, the brain never learns to merge the images coming in from both eyes in order to make a three-dimensional image.” “I don’t see in three dimensions?” He looked at me, now, squinting hard, as though expecting me suddenly to flatten out against the wall. “Well, I haven’t quite got a trained oculist’s kit”—I waved a hand at the burned-out candle, the wooden spoon, the drawn figures, and a couple of sticks I had been using—“nor yet an oculist’s training. But I’m reasonably sure, yes.
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