The mirror writing is a writing system that is to write the letters as if they were reflected by a mirror. This technique was used by Leonardo da Vinci. The experts seem to agree that Leonardo was left handed; however, he wrote in an unusual way even for a lefty.
In most texts he started writing at the right and continued to the left and letters are inverted (back to front).It is not clear if this style of writing was intentional to keep his notes private and safe (he designed tanks and other warfare machines after all). It is more likely that he did it because if you are left handed you don't have to write over your words making a mess pressing your hand over wet ink and because it is easier to pull the pen than to push it.
But that was not all, Leonardo would sometimes combine words and even invent new ones, he didn’t use punctuation often and used contractions and shorthand symbols. On recent years, the theory that Leonardo Da Vinci was also dyslexic is gaining supporters because mirror writing seem to be easier to people with dyslexia.