Leonardo's Signature

Leonardo's signature detail is a knotted thread that he includes in his paintings. "vinci" means "knot".

In our gallery tour, the guide (which was very good, btw) asked us to try and find it in each of his paintings.
one of the Italian astronomers had a very hard time finding it, as he kept looking for a signature signature, and was very frustrated when he couldn't find the name 'leonardo' scribbled anywhere, and everybody else could detect the 'signature' right away... when i explained to him what the guide meant by signature, and pointed out all those knots that we saw (one in the hair, one in the sleeve, one in the garment...) he explained that now he understand why I find all those supernovae.