A Mirror Has No Left

Read the word on your shirt in the mirror. You can't - it is backwards. And you already know why: a mirror flips left and right. Everybody knows that. It does not do that. It has never done it, not once, to anybody. Lie down on your side in front of it. Your reflection lies down too, on the same side, head at the same end. If the mirror really swapped your left with your right, then turning yourself a quarter turn should have made your head and your feet trade places. They did not. They never do. Point up: your reflection points up. Point to your left: your reflection points to your left, the same way, the same side of the room. Now point at the mirror. There it is - that is the only direction that changed. A mirror takes everything in front of it and turns its depth inside out. What was near becomes far. Nothing else moves at all. So why does the writing come out backwards? Watch your own hands do it. Write a word on a piece of paper, look at it, then hold it up to the glass - and there, you have already done it. To show that page to the mirror you had to turn it round. That turn is where the reversal happened. Not the glass. Your wrists. Hold the page up to a window instead and read it from behind, through the paper: backwards, exactly as backwards as the mirror had it. The mirror has been agreeing with the back of the page the whole time. The reason everybody says it anyway is that a reflection does not look like a picture. It looks like a person - and when you compare yourself with a person you imagine walking round to stand where they are. That walk is the swap. Turning round swaps left and right; it always has, mirror or no mirror. There is one thing in the glass that really is different. Hold up your left hand and your reflection holds up a right one - and that you cannot undo by walking round. Take a left glove, turn it any way you like, and it is still a left glove. The same thing, at the scale of a single molecule, is why one of them smells of spear