Mirror Writing

Leonardo wrote in Italian using a special kind of shorthand that he invented himself. People who study his notebooks have long been puzzled by something else, however. He usually used "mirror writing", starting at the right side of the page and moving to the left. Only when he was writing something intended for other people did he write in the normal direction.

Here is a sample of Leonardo's writing as it appears in his drawings.
This is how it would look reversed by a mirror.

People who were contemporaries of Leonardo left records that they saw him write and paint left handed. He also made sketches showing his own left hand at work. Being a lefty was highly unusual in Leonardo's time. Because people were superstitious, children who naturally started using their left hands to write and draw were forced to use their right hands.

No one knows the true reason Leonardo used mirror writing, though several possibilities have been suggested:

• He was trying to make it harder for people to read his notes and steal his ideas.
• He was hiding his scientific ideas from the powerful Roman Catholic Church, whose teachings sometimes disagreed with what Leonardo observed.
• Writing left handed from left to right was messy because the ink just put down would smear as his hand moved across it. Leonardo chose to write in reverse because it prevented smudging.