The painting was ordered by the woman's husband.
In the mid-1490s, the renowned scientist designed the so-called Leonardos robot or mechanical knight, a humanoid automaton which could sit, stand and move its arms - independently.
Robots, what da Vinci built were not robots in the modern sense.
His son, he thought, was spending too much time studying rocks and plants, watching birds to find out how their bodies work, and building models of machines.
But Leonardo stayed on as his teachers helper.