caption: The image shows a piece of paper with a drawing of a man's face on it, which is believed to be Leonardo da Vinci's signature from the 15th century. The paper is yellowed with age and the drawing is done in black ink. The text on the paper is written in a cursive font and is surrounded by a decorative border. The man in the drawing has a serious expression on his face, and his eyes are focused intently on something in the distance.