Any list of the world's top ten most famous paintings will surely include da Vinci's Mona Lisa.
在任何世界名画前十名的列表中，一定都会有达芬奇的“蒙娜丽莎”。
Part of the painting's appeal is its mystery.
其吸引力部分来自于它的神秘。
Those lucky enough to have an unobstructed view of the Mona Lisa at the Louvre often stare in awe, baffled by the smile that seems to flicker and fade.
那些有幸可以在卢浮宫自由欣赏蒙娜丽莎的人们眼神中常常都充满了敬畏，他们也对蒙娜丽莎那看似一闪即逝的微笑也感到困惑。
Gazing at a reproduction of the workproduces the same effect.
即使看它的复制品也会产生同样的效果。
Now she's smiling, now she's not.
似笑非笑。
What's the deal with Mona Lisa's smile?
蒙娜丽莎的微笑是怎么回事呢？

Harvard neuroscientist Margaret Livingstone is pretty sure she's solved the puzzle.
哈佛大学的神经科学家Margaret Livingstone很确信自己已经解开了这个疑惑。
Presumingnothing, Livingstone reasoned that the famous portrait's flickering smile is caused by the way we see.
其实没什么其它原因，Livingstone将蒙娜丽莎这个著名画像的如闪即逝的微笑的原因归为我们看它的方式。
Our eyes use two separate regions to see.
我们是用两个分隔开的眼睛看东西的。
One is the fovea, a central area used to see colors andpick out details such as fine print.
一个就是视网膜中央凹，一个用来看颜色并察觉出细节的中间地带。
The area around the fovea is better at detecting motion,shadows, and stark, black and white contrasts.
而这个区域周围的地方则更擅长察觉位移、影子、光亮及黑白对比。
When we look at a person's face, according to Livingstone, we usually focus centrally on the eyes.
照Livingstone所说，当我们在注视一个人的脸时，我们经常都会集中注意在眼睛上。
Gazing at Mona Lisa's eyes, our less accurate peripheral vision notices the mouth, picking upshadows from the cheekbones.
在凝视蒙娜丽莎的眼睛时，我们并不是那么精准的外围视力就注意在嘴巴上了，而嘴巴上则覆有脸颊骨的阴影。
The shadows play visual tricks, hinting at the curve of a smile.
就是这个阴影在视觉上给我们开了玩笑，它隐藏了微笑的曲线。
But when we look directly at themouth, our central vision doesn't see the shadows, and so the smile suddenly disappears.
但当我们直视她嘴巴的时候，我们的中心视力并不能看到该阴影，所以微笑就立刻消失了。
As oureyes scan different parts of the portrait, Mona's smile seems to fade in and out.
随着我们眼睛看画像部位的不同，蒙娜丽莎的微笑也就时有时无。
Did da Vinci intend to create this flickering smile effect?
是达芬奇有意营造这么一个“似笑非笑”的效果吗？
Perhaps. In any case, he was geniusenough to paint shadows subtle enough to astound viewers for half a millennium.
或许吧。反正，他的天赋好的让他将阴影画的如此微妙，细致到震惊了半个世纪的观赏者。
Meanwhile,Mona Lisa will keep smiling. And not.
同时，也让蒙娜丽莎的笑一直这样时有时无。