It is well-documented that Leonardo, who lived between 1452 and 1519, often wrote in mirror writing, either in an attempt to stop his rivals stealing his ideas or in a bid to hide his scientific theories, often deemed as subversive, from the powerful Roman Catholic Church.
But now a group known as The Mirror of the Sacred Scriptures and Paintings World Foundation believes that he applied the same technique to some of his best-known creations, including the Mona Lisa and the Last Supper, to conceal mysterious faces and religious symbols.
I suppose it was only a matter of time. Unsurprisingly, the "mirroring" technique has been used tirelessly in an effort to make sense of intriguing formations on the surface of Mars. I hesitate to call it an invalid research tool, but it's fraught with unique aesthetic difficulties.