ELI5: Why Is the Mona Lisa Smiling?

The Mona Lisa is smiling because she is sharing a quiet, happy moment with the painter, just like the gentle smile you give your parents when they take your picture on a nice day.

Think about what happens when you try to pose for a family photo:

• Holding still is hard: If someone tells you to say "cheese" with a giant grin, your face gets tired after just a few seconds, and the smile starts to look fake.
• Relaxing makes a better picture: Instead of forcing a huge laugh, a small, gentle smile is easy to hold for a long time. The real woman in the painting, named Lisa, had to sit still for hours, so a tiny grin was the most comfortable expression to keep.
• A secret joke: Sometimes, you might smile quietly because you are thinking of a fun memory or a secret joke that nobody else knows. The artist, Leonardo da Vinci, even hired musicians and clowns to play music and tell jokes in his room so she would feel relaxed and entertained instead of bored.

• When you look right at her lips, the smile seems to disappear because the corners of her mouth are painted very softly.
• When you look into her eyes, your peripheral vision (the edges of your eyesight) catches the soft shadows on her cheeks, making her mouth look like it is smiling again.