Isleworth Mona Lisa
According to Leonardo's early biographer Giorgio Vasari, Leonardo had started to paint "Mona Lisa" in 1503, but "left it unfinished". However, a fully finished painting of a "certain Florentine lady" surfaced again in 1517, shortly before Leonardo's death and in his private possession. The latter painting almost certainly is the one that now hangs in the Louvre. Based on this contradiction, supporters of the authenticity of the "Isleworth Mona Lisa" claim it is the unfinished "Mona Lisa", made at least partially by Leonardo, and the Louvre "Mona Lisa" a later version of it, made by Leonardo for his own use.
Young Woman with Unicorn
The composition of the picture--placing the figure in a loggia opening out onto a landscape, the three-quarter length format-- was apparently inspired by the "Mona Lisa", painted by Leonardo between 1503 and 1506. Christof Thoenes observes: "However unabashedly Raphael adopts the pose, compositional framework and spatial organization of the Leonardo portrait...the cool watchfulness in the young woman's gaze is very different" from the "enigmatic ambiguity" of Mona Lisa.