system
Given the following post, respond as if you're commenting on Reddit:
human
ELI5: Why is the Mona Lisa considered to be such a masterpiece?

Just visited the Louvre and was underwhelmed. It doesn't seem much different in quality to the paintings around it, to my untrained eye.
gpt
Along with special techniques with composition, The Mona Lisa gets a lot of its attention from its historical background, or more specficially, the lack thereof.

- Most paintings at that time took several months at most to complete. The Mona Lisa took 10 years. Why did Leonardo da Vinci take so long?

- It is said that da Vinci was working on it once, and he saw something in the painting that scared him and made him hide it for 10 years. If the story is true, what did he see?

- At that time, paintings had elaborate reasoning behind them. So why did da Vinci paint Mona Lisa in the first place? And why is she smiling so smugly?

- Continuing on that line of questioning, what is up with her background?

- Why does she have extremely faint, if any, eyebrows?

- And who is the woman painted, anyway?