Leonardo da Vinci was a great scientist as well a great artist. He possessed excellent memory and very lively imagination. His work shows integrity and belief in his self expressions.
I am quite sure that the painting's subject is Leonardo's mother Caterina in a distant memory. She died in 1495. Lisa del Giocondo's job was to be the model only.
At the time that Leonardo painted the portrait of his mother, whom he adored, she was not among the living. This is the reason why Leonardo chose the setting of the Holy Land, as he imagined it, as the background to the portrait. (The Jordan River is painted to her right and the Sea of Galilee to her left). See: Cross and Yarn-Winder.
The idea is that she was alive in Leonardo's imagination.
Therefore it is possible that Leonardo encoded the letters C and L (Caterina and Leonardo), in his special reverse style, in Mona Lisa's embroidery on her dress.
During Italian Renaissance Leonardo's time, it was not acceptable to paint ordinary people, only important people or saint.
The woman appearing in the portrait known as Isabella d'Este is actually Leonardo's mother Caterina in distant memory. The woman appearing in the portrait looks like the Mona Lisa and not like Isabella d'Este. See: Titian, Isabella d'Este, 1534 - 1536. This cartoon which has survived must have been drawn for an important work. See the cartoon in London, National Gallery. The only possible important work we are aware of is the Mona Lisa. Thus, Leonardo glorifies his mother as a respectable woman. See also the veil and the upper dress cut, rounded and not in straight lines.
I reached these conclusions during my research about Leonardo's art which started in 1976.
All rights reserved