Technically, it is called “Codex Forster”, named after the English writer John Forster, who collected the notes written by Leonardo da Vinci while he was alive: a work that resulted in three books, donated to the Victoria & Albert Museum after his death. Recently the museum activated a team to digitalize Leonardo’s notes, in order to preserve them for a longer time (since they are extremely fragile and delicate). The digitalization of the first book is completed and the result is available online, directly on the website of the museum, at the link below.
The first book includes the notes taken by Leonardo from 1487 to 1490 in Milan and the ones written in Florence in the end of his life, around 1505. Watching them not only you have the opportunity to get in touch with Leonardo’s creativity in science (those are the notes about hydraulics and physics), but also you can observe his famous mirror writing: the handwriting goes from right to left, and the only way to read it is by looking at the text through a mirror.
The reasons why Leonardo was writing in that way were discussed a lot over the years. On one hand, there is a theory according to which he did so in order to make the notes more difficult to understand, preventing the others to steal his ideas, but this theory is nowadays considered unlikely: if Leonardo was really concerned that somebody would steal his insights, he would have easily invented a complete secret code understandable only to him. It’s more likely that Leonardo was writing backwards because he was left-handed, and using the left hand it was better to go in the opposite direction, avoiding to touch the ink with the hand while writing.
The digitalization of the other two Codex Forster has already started and the museum is enthusiastic about the idea that this precious work can survive forever, even another 500 years: it would have been impossible relying only on paper.