A few years back, I saw “Mona Lisa” in person.

After roughly twelve years spent swamped in the painting’s fanfare, I was wholeheartedly underwhelmed: it was a technical masterpiece, of course, but I didn’t see any of the proclaimed magic. It was a good four years before I started to learn how this painting had captured the public’s heart for the past six centuries.

“Mona Lisa” is as much a work of science as one of art. Da Vinci was a brilliant student not only of oils and inventions, but of humanity. Her famed mysterious smile is an intricate use of biology and psychology, a product more of Da Vinci’s mind than his hand. The foveal region of the human eye (the section of the retina that perceives the greatest detail) is tiny compared to our field of vision. Da Vinci took advantage of this: the corners of her mouth are subtly downturned, as in a neutral resting position; therefore, when the viewer focuses on it, catching the detail of her lips, her smile momentarily vanishes. But when focusing on any other section of the painting, her mouth is pushed to the periphery, and a faint smile returns. Try to chase it back to her lips, and it’s once again gone, back to a neutral position. The trick imbues her smile with a sense of charming elusiveness -- frustration finds its antidote in wonder.

Though not so much a trick as simple attention to detail, Da Vinci was able to construct the lighting so as to give “Mona Lisa” the impression of always looking at the viewer. How we see light and shadow, particularly how it catches in the eyes and collects around facial features, changes subtly with the angle of perception. Da Vinci managed to manipulate these features to give her the impression of perpetually facing the viewer, no matter what angle they admired her from.

Perhaps most clever, however, is Da Vinci’s fabrication of quietly dissimilar expressions in her eyes and mouth. The difference is subtle enough that with one in the periphery, the painting still feels coherent and complete, the interpretation of one feature dictated by the other. But by shifting your focus, your sense and understanding of each shifts as well. In trying to reconcile the two expressions, the disquieted mind seeks an answer in amazement.