the third wife of wealthy silk merchant Francesco.The smile of Mona Lisa has kept people guessing.It's said that the smile originated from Leonardo's mother, Caterina.While others say the smile is quite simple because women were taught to smile to add an air of mystery and elegance.③The truth is that this style of smile was not invented by da Vinci.It can be found in a number of sculptures from the 15th century. Anyone except da Vinci himself can't know the truth behind this famous painting，but people are so fond of it and would enjoy guessing.